Nanoelectronics is a multidisciplinary branch of science and technology that focuses on using nanotechnology in electronic components. Systems and gadgets that can function down to nanoscale dimensions are usually referred as nanoelectronic. It is believed that nanoelectronics are substantially smaller than 100 nanometers. As the bounds of physical microelectronics using silicon approach their limits and performance levels, the field of nanoelectronics continues to develop techniques to construct ultra-small, highly effective, and energy-efficient electronic devices. Nanoelectronics uses ideas from quantum mechanics, materials science, and electrical engineering to alter matter at the atomic and molecule level.

The area of nanotechnology known as "nanoelectronics" is devoted to electronic systems and components that make use of nanoscale materials and architectures [1]. Compared to conventional microelectronics, it uses the special qualities of materials at the nanoscale to produce electronic devices that are faster, smaller, and more effective [2].

Concepts to Nano Electronics

Quantum mechanics and tunneling

Quantum Mechanics and Tunneling: Nanoelectronics is based on predictions from quantum mechanics [3]. Particles like electrons no longer exhibit classical behavior in accordance with Newtonian physics once they reach the nanoscale. Rather, they display quantum behavior; hence, the quantum characteristics of electrical devices at the nanoscale must be taken into account [4]. Quantum tunneling, in which electrons can tunnel over energy barriers that would be impossible under classical principles, is without a doubt the most straightforward example [5]. This manifests as a decrease in the size of the transistor gates from a few nanometers to a few nanometers, which changes how they switch and may cause leakage currents [6]. The fact that electrons are confined in small dimensions, which restricts their energy levels, is a basic feature of quantum confinement. This leads to changes in the electrical and optical properties of materials, creating new properties in semiconducting devices and sensors [7,8]. These are also found in new forms of computation (such as wave-particle duality, superposition, and Heisenberg's uncertainty principle) and quantum gadget characteristics [9]. The design of next-generation devices, like qubits, quantum dots, or single-electron transistors, which show a substantial body in the larger context of quantum mechanical nanoelectronics, is signaled by acknowledging and harvesting their yields [10]. Discrete energy levels, quantum tunneling, quantum confinement, and other factors start to dominate electron behavior in circuits. Moreover, the functioning and limiting limitations of sensors and nanoscale transistors depend on these events [11]. However, electrons can overcome obstacles that would be impossible in classical physics thanks to quantum tunneling and electron energy levels are changed by quantum confinement, which affects optical and electrical characteristics [12].

Dimensions and scaling

The foundation of nanoelectronics is size and scale, where significant differences in physical characteristics in relation to functionality result from additional component shrinkage [13]. The electrical, thermal, and mechanical characteristics of electronic components at the nanoscale are essentially different from those found at macro dimensions. As a result, electronics become faster and smaller while using less energy. Because electrons must travel a much shorter distance when components are smaller, processing speeds and power consumption are both accelerated [14]. Moore's law, which dictates that a chip's transistor density should double roughly every two years, is greatly aided by it. Because more functionality can fit in a smaller space, nanoscale devices are dense, which makes them useful for wearables, smartphones, and smartwatches [15].However, issues including short-channel effects, increasing leakage currents, and inconsistent performance arise as scaling continues [16]. Nevertheless, attempts are underway to overcome these obstacles by the use of novel materials and device topologies, such as gate-all-around FETs, and other 3D structures [17]. All of this will eliminate scaling's drawbacks while allowing for the full benefits to be realized. The next technological paradigms and performance improvements in nanoelectronics will ultimately depend on size and scale. All mechanical, thermal, and electrical physical phenomena undergo significant change including speed up production, uses less energy, and permits high-density integration[18]. This minimizes physical space and enables the development of processors with billions of transistors for massive computing [19].

Materials at Nanoscale

Since many of the amazing features and enhanced functionality of nanoscale devices originate directly from the materials themselves, materials are crucial to Nano electronics. Conventional materials like silicon reach their performance limits at the nanoscale, and new and advanced materials with remarkable electrical, mechanical, and thermal capabilities will soon replace them [20].

Carbon nanotubes (CNTs)

Carbon Nanotubes (CNTs): are extremely conductive and stiff enough to be used in transistors, interconnects and sensors and their 1D structure yields ballistic electron transport, which is supreme [21].

Graphene

 A single layer of carbon atoms arranged in a honeycomb lattice with excellent electrical conductance, flexibility and thermal conductivity. Graphene, is the future of high electron mobility transistors electrodes and flexible electronics [22].

Quantum dots

Quantum dots: Nanoscale semiconductor particles whose optical and electronic properties can be tuned. They behave mainly by quantum confined and are common to be employed in displays, lasers and quantum computers [23].

Nanowires

Nanowires: These are ultrafine wires with diameters in the nanometer regime. Due to high surface to volume ratio and directional conduction, they make good nanoscale FETs and photodetectors when constructed using nanowires [24].

Molecular components

Molecular Components: Bioengineered organic molecules that are designed to carry out electronic functions like switching, memory storage and signal amplification. The kernel of molecular electronics, an emerging technology and one that we believe will be huge in its impact on computers [25].These materials are ideal for the creation of fast, compact, energy-saving, multifunctional devices and are crucial for taking electronics to the next level and beyond current limits by discovering, and adapting these new materials [26].

Architecture of Nanodevices

In order to take use of quantum and nanoscale effects, nanoelectronics provides a series of novel device architectures that deviate from conventional designs. This opens up a variety of new architectures that offer new uses, higher speeds, and far more compact devices than traditional ones [27].

Single-electron transistors (SETs)

 Single-electron manipulation devices based on the phenomena (Coulomb blockades), they have a very high sensitivity and are ideal for applications involving low power consumption or nanoscale charging detection [28].

Molecular Fets (families of FETs)

 Rather than using conventional semiconductor characteristics, the semiconducting channel in these transistors is only a single molecule utilized to regulate current flow. They are an excellent option for upcoming ultra-dense circuits due to their shrunken size and tunability [29]. - Tunnel FETs are next-generation transistor design that improve leakage currents and power loss [30] - Fin FETs are a 3-D structure which helps in better gate Control and tunnel FETs use quantum tunneling to switch states using lower voltages [31].

Spintronic devices

The intrinsic spin of an electron, rather than only its charge, is used in the spin-based form of electronics. Magnetic tunnel junction (MTJ) spintronic topologies are crucial in MRAMs that offer low power, switching speeds, and non-volatile functionality [32].

Memristor

These devices store memory of how much total charge has passed through them. They can potentially be used in neuromorphic computing systems if it is possible to map them as both memory and logic elements [33].

Critical Technologies for Nanoelectronics

Molecular electronics

Molecular Electronics: The study of individual molecules or nanoscale molecular structures in electronic applications is known as molecular electronics [34]. These molecules might function similarly to common parts like transistors, switches, and diodes. These could aid in the development of storage systems with high density and quick computing because to their size possibilities designed to get beyond the limitations of traditional silicon-based electronics in terms of downsizing [35]

Nanotube based transistors

Nanostructure with exceptional mechanical strength and electrical conductivity is carbon nanotubes (CNTs) [36]. CNTs have substantially quicker operation speeds and reduced energy usage in transistors than existing silicon-based transistors. They are therefore a strong contender for the upcoming generation of high-performance electronics [37].

Graphene integrated devices

 Graphene integrated devices: A single layer of carbon atoms organized in a honeycomb lattice makes up 2D graphene. Its thermal conductivity and electron mobility are exceptional [38]. Because of these qualities, graphene is utilized in transistors, sensors, and flexible electronics, making it a viable option for sophisticated systems that are not limited by their conventional speeds and efficiency [39]

Quantum dots

Quantum dots are incredibly tiny semiconductor particles, roughly one nanometer in size. Their remarkable electrical characteristics are caused by quantum confinement, but they may be adjusted [40]. The characteristics are ideal for high-end display systems that employ quantum dots, quantum computers, and high-performance solar cells [41].

Spintronics

Spintronics, or spin electronics, refers to field of technology based on exploitation of the intrinsic spin of electrons rather than their charge for storing and processing information [42]. Spintronics-based devices are faster than today's most sophisticated electrical devices, and so spintronics is a key technology for next generation computing [43].

Applications of Nanoelectronics

Computers

The development of modern computers is largely driven by nanoelectronics. Used nanometers to reduce the size of the transistors, enabling more energy-efficient and power-intensive computation. This tendency of shrinking makes it possible to implement billions of transistors on a single chip, which significantly increases computing performance and lowers power consumption [44]. Additionally, it is required for nanoelectronics in high-end GPUs and multi-core CPUs that can perform AI, data analysis, or just rapid graphics. It supports the development of neuromorphic systems that attempt to replicate the high efficiency of the human brain as well as 3D chip designs [45].

Data storage

Nanoelectronics has revolutionized data storage by offering dependable, high-density, ultrafast memory devices that may be inexpensive [46]. The speed, size, and longevity of conventional memory systems are essentially limited. Despite these drawbacks, advanced materials and quantum mechanical processes allow nanoelectronic memory systems, such as magneto resistive RAM (MRAM), resistive RAM (ReRAM), and nano-scale flash memory, to store data at the atomic level [47]. Compared to conventional storage facilities, both are more robust, quicker, and non-volatile. In order to store more data in a smaller form factor—a necessity for mobile devices, high-performance computing, and artificial intelligence—nanoelectronics is also crucial [48]. With continued advancements, nanoelectronic memory will play a crucial role in next-generation storage systems, such as neuromorphic and quantum computing [49].

Medical

By enabling ultra-sensitive, small-footprint, low-power leveling, diagnostic, and therapeutic subsystems, and nanoelectronics has had a significant impact on the medical and biomedical fields [50]. Implantable nanoelectronic sensors can detect vital signs or disease biomarkers and allow real-time health monitoring and illness intervention [51]. Lab-on-a-chip systems build a microchip with a variety of diagnostic capabilities that enable quick and precise testing of, albeit in small quantities, the majority of illnesses including infections, malignancies, or genetic anomalies [52]. Drug delivery systems with smart nanoelectronics capabilities also make it possible to deliver or release medications in a very site-specific way with few negative effects. They are a part of the trend toward personalized medicine, where a patient's therapy may become highly customized [53]. In parallel, nanoelectronics is being investigated for brain interfaces and prosthetics to improve device communication into the human nervous system [54].

.

Flexible electronics

 A peek of nanoelectronics is made possible by flexible electronics, a novel method of integrating electronic gadgets into our daily lives because they are designed at that scale. Organic semiconductors, carbon nanotubes, and graphene-based devices that can undergo continuous deformation without compromising circuit function are among the thin, flexible, and stretchable materials used in these technologies [55]. Wearable health monitoring, foldable smartphones that are flexible and dynamic, electronic skin (e-skin) for prosthetics, and smart fabrics that can incorporate sensors as actuators are examples of flexible electronics applications [56]. On the other hand, the Nano electronic components ensure conformal and dynamic operation over complicated surfaces because they are lightweight and have a configurable design. Additionally, the systems' low power consumption and ease of portability make them suitable for continuous use with real-time data collecting [57]. Flexible electronics may ultimately impact robotics, fashion, healthcare, and even IoT (Internet of Things) interfaces thanks to grassroots advancements in material science and nanofabrication [58].

Quantum

The foundation of quantum computing, a revolution in information processing, is Nano electronics. The fundamental components of quantum computers are qubits, or quantum bits, and quantum computation carried out utilizing superpostional and entangled principles [59]. High accuracy and minimal energy loss: Qubits are constructed, interfaced, and read out using Nano electronic components [60]. Significant research is being done on developing scalable and stable qubit platforms for many technologies, such as quantum dots, Josephson junctions, and topological insulators, which suggests that a lot of work is being done on classical error correction [61]. Second, the shrinking of ancillary systems like quantum interconnects and control circuits is supported by Nano electronics. As a result, quantum computing will advance toward really application-ready cryptography, medicine development, climate modeling, and the resolution of challenging optimization issues [62]. A crucial step toward quantum supremacy and the computers of the future is the incorporation of Nano electronics into quantum computing.

Advantages of Nanoelectronics

Miniaturization

Nanoelectronics enables the creation of extremely small components, allowing electronic devices to become more compact and portable. This miniaturization supports the development of wearable technology, smaller sensors, and advanced medical devices, all while maintaining or even improving performance [63,64].

Faster High performance

Nanoscale properties such as shorter electrical paths and less capacitance means that Nano electronic devices are expected to run at orders of magnitude higher speeds and on much less power. This ultimately gives better system-level performance so they are great for systems needing high performance and energy efficiency [65].

Cost-effectiveness (long term)

While it is true that the initial implementation can't be so cheap, there is a big promise for large-scale manufacturing in Nano electronics. Over the longer term, as more volume production costs are captured over time through scaling production we expect material costs will be lower albeit still relatively high, advanced technologies will get more affordable [66].

Novel function

Nano electronics provides access to new possible architecture and functionalities of devices. Flexible electronics, bio-integrated devices and systems are some of those which were never feasible by traditional silicon-based technologies and have opened up unbounded innovations in different areas [67].

Challenges in Nano electronics

Fabrication limitations

A major bottleneck in Nano electronics is the inability to fabricate at atomic scale. Advanced technologies and highly controlled or a calibrated environment demands to manipulate materials of that level which both cost a lot and difficult to implement on industrial scale [68].

Thermal Management

At the nanoscale heat is harder to manage. Excessive heat can degrade the performance and reliability of devices. For stable operation and avoiding damage to the delicate Nano electronic components, thermal regulation is essential [69].

Quantum phenomena

As electronic components get smaller and smaller down to the nanoscale, more and more quantum effects become intrinsic (electron tunneling/leakage are two examples). Not all of these secondary effects, accidents nearly all cause instability and the meta-performance issues that lead design into unknown territory [70].

Maintaining performance and durability

Maintaining uniform Performance and longevity at nanoscale is a hard task to tackle. The components must be able withstand operational abuse, as well as the environment without degenerating as the size of components shrink [71].

Integration

The actual integration of nanoelectronic components with today's microelectronics is rather difficult. Challenges to the integration of nanoelectronic systems are compatibility issues and there is the whole fabrication skills discrepancy of scaling [72].

Thus, Nanoelectronics holds promising future with improved and functionally enhanced nanodevices offering applications in numerous disciplines

1. Lu W, Lieber CM.  Nano electronics from the bottom up. Nature materials. 2007; 6: 841-850.
2. Compano R, Molenkamp L, Paul DJ. Roadmap for nano electronics. Euro Commi IST prog Future Emerg Technol. 2000; 1-81.
3. Rubakov VA. Quantum mechanics in the tunneling universe. Phy Letters B. 1984; 148: 280-286.
4. Schreiner PR. Quantum mechanical tunneling is essential to understanding chemical reactivity. Trends in Chemi. 2020; 2: 980-989.
5. Merzbacher E. The early history of quantum tunneling. Phy Today. 2002; 55: 44-49.
6. Fermor JH. Quantum-mechanical tunneling. Am J Phy. 1966; 34: 1168-1170.
7. Razavy M. Quantum theory of tunneling. World Scient. 2013.
8. McKagan SB, Perkins KK, Wieman CE. Deeper look at student learning of quantum mechanics: the case of tunneling. Physical Review Special Topics - Phy Educat Res. 2008; 4: 020-103.
9. Ancona MG. Macroscopic description quantum-mechanical tunneling. Phys Rev B.1990; 42: 1222.
10. Andreassen A, Farhi D, Frost W, Schwartz MD. Direct approach to quantum tunneling. Phy Rev Letters. 2016; 117: 231-601.
11. Bachas C, Lazarides G, Shafi Q, Tiktopoulos G. Quantum mechanical tunneling at high energy. Phy Letters B. 1991; 268: 401-407.
12. Riga J, Seviour R. Electromagnetic analogs of quantum mechanical tunneling. J Applied Phy. 2022; 132.
13. Arts K, Hamaguchi S, Karahashi K, Knoops HC, MacA J, Kessels WM. Foundations of atomic-level plasma processing in nanoelectronics. Plasma Sources Sci Tech. 2022; 31: 103002.
14. Gedam V, Pimplapure A, Sen P, Namdeo Y, Mishra TK, Sahu PK. Quantum confinement nanostructures: Foundations frontiers in nano science and nanotechnology. Cahiers Magellanes-Ns. 2024; 6: 5727-5734.
15. Roco MC. National Nanotechnology Initiative at 20 years: enabling new horizons. J Nanoparticle Res. 2023; 25: 197.
16. Ahmadpour SS, Noorallahzadeh M, Al-Khafaji HMR, Darbandi M, Navimipour NJ, Javadi B, et al. A new energy-efficient design for quantum-based multiplier for nano-scale devices in internet of things. Compu Electri Eng.  2024; 117: 109263.
17. Zhang Y. H, Wu LR, Ma J, Cui G. Nanotechnology in solid state batteries, what’s next? Next Nanotec. 2023; 2: 100011.
18. Huang X, Auffan M, Eckelman MJ, Elimelech M, Kim JH, Rose J, et al. Trends, risks and opportunities in environmental nanotechnology. Nature Rev Earth Envi. 2024; 5: 572-587.
19. Khanna VK. Integrated nanoelectronics. Nano Sci Technol.  2016; 10: 978-81.
20. Madkour LH.  Nanoelectronic materials: fundamentals and applications Springer. 2019.
21. Pandey G, Rawtani D, Agrawal YK. Aspects of Nano electronics in materials development. Nanoele materials devel. 2016; (10.5772/64414).
22. Singh R, Kumar D, Tripathi CC. Graphene: Potential material for Nano electronics applications. Indian J Pure Appl Phys. 2015; 53: 501-513.
23. Bimberg D. Quantum dot-based Nano photonics and nano electronics. Elect Letters. 2008; 44: 168-171.
24. Ferry DK. Nanowires in nanoelectronics. Science. 2008; 319: 579-580.
25. Vuillaume D. Molecular Nano electronics. Proceedings of the IEEE. 2010; 98: 2111-2123.
26. Lyshevski SE. Nano and molecular electronics handbook. CRC Press. 2018.
27. Di Bartolomeo A. Electronic Nano devices. Nanomat. 2022; 12: 2125.
28. Kastner MA. The single-electron transistor. Rev Modern Phy. 1992; 64: 849.
29. Li P, Jia C, Guo X. Molecule?Based Transistors: From Macroscale to Single Molecule. The Chem Record. 2021; 21: 1284-1299.
30. Avouris P. Molecular electronics with carbon nanotubes. Accounts Chem Res. 2002; 35: 1026-1034.
31. Li H, Shi W, Song J, Jang HJ, Dailey J, Yu J. Chemical and biomolecule sensing with organic field-effect transistors. Chem Rev. 2018; 119: 3-35.
32. Hirohata A, Takanashi K. Future perspectives for spintronic devices. J Phy D: Applied Phys. 2014; 47: 193001.
33. Xiao Y, Jiang B, Zhang Z, Ke S, Jin Y, Wen X. review of memristor: material and structure design, device performance, applications and prospects. Sci Techno Adva Materials. 2023; 24: 2162323.
34. Mathew   PT, Fang F. Advances in molecular electronics: a brief review. Eng. 2018; 4: 760-771.
35. Heath JR, Ratner MA. Molecular electronics. Phy today. 2003; 56: 43-49.
36. Bondavalli P, Legagneux P, Pribat D. Carbon nanotubes-based transistors as gas sensors: State of the art and critical review. Sensors   Actuators B: Chemi. 2009; 140: 304-318.
37. Tang J. Carbon nanotube-based flexible electronics. Flexible, Wearable, Stretc Elect. 2020; 137-156.
38. Ruhl G, Wittman S, Koenig M, Neumeier   D.  The integration of graphene into microelectronic devices. Beilstein j nanotech. 2017; 8: 1056-1064.     
39. Wang X, Gan X.  Graphene integrated photodetectors and opt-electronic devices a review. Chinese Phy B.  2017; 26: 034203.
40. Tsu R.  Challenges in nanoelectronics. Nanotec. 2001; 12: 625-628.
41. Khanna VK. Integrated nanoelectronics. NanoSci. Technol, 2016; 10: 978-81.
42. Pulizzi F.  Spintronics. Nature materials. 2012; 11: 367-367.
43. Bader SD. Parkin SSP. Spintronics. Annu. Rev. Condens. Matter Phys., 2010; 1: 71-88.
44. Morris JE, Iniewski K. Nanoelectronic device applications handbook.2013.
45. Sheu B, Wu PCY, Sze SM.  Special issue on nanoelectronics and nanoscale processing. Proce IEEE, 2003; 91:1747-1752.
46. Yu B, Meyyappan M. Nanotechnology: Role in emerging nanoelectronics. Solid-state elect. 2006; 50: 536-544.
47. Rajendran J, Karri R, Wendt JB, Potkonjak M, Rose GS, Wysocki B.  Nano meets security: Exploring Nano electronic devices for security applications. Proceedings of the IEEE. 2015; 103: 829-849.
48. Puers R, Baldi L, Van de Voorde M, Van Nooten SE. Nano electronics: Materials, Devices, Applications, 2 Volumes. John Wiley & Sons. 2017.
49. Chen A, Hutchby J. Zhirnov V, Bourianoff G. Emerging nano electronic devices. John Wiley Sons.2014.
50. Cohen-Karin T, Langer R, Kohen DS. The smartest materials: the future of Nano electronics in medicine. ACS Nano, 2012; 6: 6541-6545.
51. Offenhäusser A, Rinaldi R. Nano bioelectronics-for Electronics, Biology, and Medicine. Springer Science & Busi Media. 2009.
52. Haleem A, Javaid M, Singh RP, Rab S, Suman R. Applications of nanotechnology in medical field: a brief review. Global Health J.  2023; 7: 70-77.
53. Homberger M, Simon U. On the application potential of gold nanoparticles in Nano electronics and biomedicine. Philosophical Transactions of the Royal Society A: Mathematical, Phys Eng Sci. 2010; 368: 1405-1453.
54. Gopinath SC, Lakshmipriya T, Arshad MM, Uda M NA, Al-Douri Y. Nano electronics in biosensing applications. In Nano biosensors Biomole Targ Elsevier. 2019; 211-224.
55. ZhuW, Park S, Yogesh, MN, Akinwande, D. Advancements in 2D flexible Nano electronics: from material perspectives to RF applications. Flexi Prin Electr. 2017; 2: 043001.
56. Aftab S, Hussain S, Al?Kahtani AA. Latest innovations in 2D flexible Nano electronics. Advan Materials. 2023; 35: 230-1280.
57. Akinwande D, Petrone N, Hone J. Two-dimensional flexible nano electronics. Natu commu. 2014; 5: 56-78.
58. Rao Z, Wang X, Mao S, Qin J, Yang Y. Liu M, Sun B. Flexible memristor-based Nano electronic devices for wearable applications: a review. ACS Applied Nano Materials. 2023; 6: 18645-18669.
59. Arora VK. Nano electronics: Quantum engineering of low-dimensional nano ensembles. CRC Press. 2018.
60. Arora VK, Tan ML. Quantum nanoelectronics: challenges and opportunities. IEEE Intern Confer on Semicon Elect. IEEE. 2008.
61. Goser K, Glosekotter P, Dienstuhl J. Nanoelectronics and nanosystems: from transistors to molecular and quantum devices. Spri Sci Busi Media.2004;
62. Filippatos PP, Chroneos A. perspective of doping in diamond: From Nano electronics to quantum applications. J Applied Phy 2025; 138.
63. Bhatia S, Raman A, Lal N. The shift from Microelectronics to Nanoelectronics: a review. Internat J Advanc Res Comp Communic Engin, 2013; 2: 11-18.
64. Kaur I, Yadav S, Singh S, Kumar V, Arora S. Bhatnagar D. Nano electronics: a new era of devices. Solid State Phenomena. 2015; 222: 99-116.
65. Cohen-Karni T. Langer R.  Kohen DS. The smartest materials: the future of Nano electronics in medicine. ACS nano, 2012; 6: 6541-6545.
66. Goldhaber-Gordon D, Montemerlo MS, Love JC, Opiteck GJ, Ellenbogen JC. Overview of nanoelectronic devices. Proce of the IEEE. 1997; 85: 521-540.
67. Forshaw M, Stadler R, Crawley D, Nikolic K. short review of Nano electronic architectures. Nanotech. 2004; 15: S220-S223.
68. WONG HSP.  Nano electronics–Opportunities and challenges. Inter J high speed elect systems. 2006; 16: 83-94.
69. Brozek T. Micro-and Nano electronics: Emerging device challenges and solutions. CRC Press.2014.
70. Wang KL. Issues of Nano electronics: A possible roadmap. J of Nanoscie Nanotech.  2002; 2: 235-266.
71. Claeys   C. Trends and challenges in micro-and Nano electronics for the next decade. In Proceedings of the 19^th Int Confer Mixed Desi Integr Circ Systems-MIXDES IEEE. 2012; 37-42:
72. Arora VK, Tan ML. Quantum nano electronics: Challenges and opportunities. IEEE Interna Conf on Semicon Elect IEEE. 2008; 1-6.