ENEE702 - Advanced Electronic Materials and Devices

Fall 2005

Instructor:

 

C.H. Yang, 301-405-3673, email: yang@eng.umd.edu

 

  • Prerequisite: ENEE 480 or equivalent.
  • Class time and place: Tuesday and Thursday, 12:30 to 1:45p.m., Room1110, Kim Eng. Building
  • Textbook: We will use journal publications
  • Reserved in EPSL: Books by Kittel, Kelly, Davies, and Solid State Physics v.44 (SSP)
  • Grading: To be finalized, but probably based on class room oral presentations and a final report that reviews a particular research
  • Website: http://www.ece.umd.edu/class/enee702.F2005/

 

Syllabus:

 

We will discuss the most important concepts in semiconductor heterojunctions, with an emphasis on quantum devices. Both basic properties and their device applications will be discussed. The basic properties include the band structure, transport theory, Bloch state, size quantization, quantum Hall effect, Coulomb charging effect, tunneling, etc. For device applications, we will discuss quantum wires, quantum dots, resonant tunneling diodes, single electron transistors, and computation by single spin. Unique fabrication techniques for these nanoscale devices such as molecular beam epitaxy and electron beam lithography will be briefly summarized. Core topics are listed below. For each topic, we will review the theoretical aspects and the corresponding experimental demonstrations.

 

Handouts:

Presentations:

Topics:

 

Electronic states in bulk semiconductors (a brief review of what’s covered by enee702, refer to Kittel)

  • Key concept --- bandgap and doping
  • Bloch theorem
  • Band structure calculated by the tight-binding picture
  • The k×p model
  • Band edge effective mass theorem
  • Shallow donor and acceptor energy levels
  • Standard semiconductor bulk physics
  • Standard device equations: electrostatic and current continuity equations
  • Nonparabolicity
  • Transport theory: only Fermi electrons count

Electronic states at the heterojunctions

  • Key concept --- Band alignment, explained by the interfacial dipole model
  • The envelope function theory

Two-dimensional electrons

  • MIS system (silicon MOS capacitor), calculation of 2D states
  • Doping properties in heterostructures
  • Modulation doping, structure, benefits, observation
  • Screening in 2D
  • High electron mobility
  • Electron transport properties at 2D interface
  • Landau levels
  • Magnetotransport and Quantum Hall effect
  • Other important transport phenomena

o       Vertical transport

o       Tunneling

o       Resonant tunneling

o       Optical properties at 2D interface

o       Intraband transition and interband transition

o       Absorption and photoluminescence

o       Device application: HEMT and MMIC and quantum well laser

1D: electronic and optical properties

·        1D density of states: experimental observation of quantized conductance

·        1D transport (fabrication, the ballistic or coherent nature and experimental evidence); Landauer formulism: treating transport as sequential scattering events

·        1D phase coherence, Aharonov Bohm interference, spin Berry phase experiments

·        1D devices

0D: electronic and optical properties

  • Zero-dimensional density of states
  • Experimental evidence of 0D quantum dots
  • Single electron phenomena
  • Single electron transistor: lateral and vertical versions
  • Single electron quantum noise
  • 0D device application: quantum computation using single electron spin

 

Homework:

 

2D Landau levels with Zeeman splitting  Plotting of the 2D Landau levels

 

References:

 

  1. Shallow donor states observed by photoconductivity PRL 27 989 (1971)
  2. Shallow impurity states in GaAs observed by several methods JPC 7 4164 (1974)
  3. Interface diople theory of heterojunction energy band offset PRB 30, 4874 (1984)
  4. Epitaxial metal-semiconductor (Schottky) interface JVSTB 11, 1546 (1993)
  5. Evidence of metal-induced-gap-states: LiCl on Cu PRL 90 196803 (2003)
  6. Fermi level pinning at surface: Bardeen’s model PR 71, 717 (1947)
  7. Measure of heterojunction energy band offset APL 47, 503 (1985)
  8. Band structure of bulk semiconductors: See Kittel and ENEE793 handout on tightbinding calculation and k×p theory
  9. Envelope function model: See SSP v. 44, the 2nd review paper by Bastard et al., and PRB 24, 5693 (1981)
  10. Transfer matrix technique APL 22, 562 (1973)
  11. Double barrier resonant tunneling diode APL 24, 593 (1974)
  12. Experimental evidence of a “quantum well” by photoluminescence, PRL 33, 827 (1974)
  13. Theoretical prediction of 2D layer in MOS, PR 163, 816 (1967), PRB 5, 4891 (1974)
  14. Experimental demonstration of the modulation doping scheme in a GaAs MQW, APL 33, 665 (1978)
  15. GaAs HEMT: delta-doping APL 71, 683 (1997), multiple delta-doping APL 55, 1888 (1989), simple doping profile APL 45, 695 (1984), i-HEMT APL 67, 1262 (1995).
  16. DX center in AlGaAs: PRB 37, 8298 (1988), PRB 39, 10063 (1989).
  17. Boltzman equation showing that only electrons at Fermi surfaces contribute to electrical conduction: formula: “Principles of Solids,” by J.M. Ziman
  18. Landau levels: Kittel, and “Quantum Mechanics” by Landau & Lifshitz, “Quantum Mechanics (non-relativistic theory)”
  19. Capacitance spectrum demonstrating Landau levels, in silicon MOS PRL 21, 212 (1968), and in GaAs-HEMT PRB 32, 2696 (1985).
  20. Cyclotron resonance, experimental setup PRB 52, 8654 (1995)
  21. Review on 2D systems Rev.Mod.Phys 54, 437 (1982)
  22. Thomas-Fermi (electrostatic) screening: Kittel
  23. Dynamical screening in 3D: PR 115 786 (1959)
  24. Dynamical screening in 2D and application on impurity screening at MOS interface, PRL 18, 546 (1967)
  25. Calculation of mobility of 2D electrons in Si MOS: PRL 44, 1469 (1980)
  26. Calculation of mobility of 2D electrons in Si MOS: PRL 83, 164 (1999)
  27. Experimental observation on the temperature dependence of 2DEG mobility in a GaAs HEMT, APL 45, 695 (1984)
  28. Experimental data on SOI mobility IEEE ED 48, 2842 (2001)
  29. Extremely high mobility 2DEG in a GaAs HEMT: APL 71, 683 (1997)
  30. Complication in doping GaAs --- the DX centers: PRB 46, 6777 (1992)
  31. Numerical calculation for energy levels in GaAs HEMT: PRB 30, 840 (1984)
  32. One dimensional quantized conductance PRL 60, 848 (1988)
  33. Numerical modeling and quantum wave simulation PRB 43 12638 (1991)
  34. A review of QPC Proc IEEE 79, 1188 (19991)
  35. Magnetic focusing experiment in GaAs 2DEG: PRB 39, 8556 (1989)
  36. Numerical simulation for magnetic focusing, with spin-orbit: PRB 70, 041301 (2004)
  37. Quantum Hall Effect: experimental observation in MOSFET: PRL 45, 494 (1980)
  38. Quantum Hall resistance adopted as resistance standard: im-34-2.pdf
  39. Landau Level calculation LL.pdf
  40. Quantum Hall effect edge states PRB 25, 2185 (1982)
  41. Suppression of backscattering PRB 38, 9375 (1988)
  42. Quantum Hall effect: explanation using 1D channels PRL 59 1973 (1987)
  43. Aharonov-Bohm interference: PR 115, 485 (1959)
  44. Aharonov-Bohm interference in metallic “wires”: PRL 54, 2696 (1985)
  45. Aharonov-Bohm interference in semiconductor “wires” Surface Science 196, 68 (1988)
  46. Aharonov-Bohm interference in the QH regime: PRL 60, 2074 (1988)
  47. Aharonov-Bohm interference in depleted semiconductor “wires: PRB 64, 045327 (2001)
  48. Dynamic phase change of Bosons over a ring: PRL 7, 43 (1961) and PRL 7, 46 (1961)
  49. Electrostatic AB interference experiment: PhysicaE 6, 318 (2000)
  50. Electrostatic AB interference experiment: PRB 40, 3491 (1989)
  51. Electrostatic AB interference experiment: PRB 54, 5457 (2000)
  52. Electrostatic AB interference experiment: PRL 79, 273 (1997)
  53. Multiple-lead ballistic junction experiment: PRB 46, 9648 (1992)
  54. Phase coherence experiment in carbon nanotube-ring: PRL 84, 4441 (2000)
  55. Typical 1D magnetotransport --- quenching of the classical Hall effect PRL 63, 1857 (1989), bend resistance PRL 60, 2081 (1988), theory PRL 63, 414 (1989) and classical size effect in GaAs 2DEG: experiment PRB 36, 7751 (1987); PRL 63, 2128 (1989) and magnetic depolulation: PRB 37, 10118 (1988) (plot showing 1D to 2D transistion by high magnetic field)
  56. Spin Orbit splitting of 2D subbands: PRB 38, 10142 (1988)
  57. Spin Orbit splitting of 2D subbands: PRB 57, 11911 (1998)
  58. Weak localization in GaAs 2D EG: experiment APL 49, 1781 (1986)
  59. Planar double barrier resonant tunneling APL 55, 589 (1989)
  60. Hot electron transistor (THETA): APL 47, 1105 (1985); PRL 55, 2200 (1985)
  61. Double-barrier injector hot electron transistor (RHET): APL 49, 1779 (1986); Phil trans 354, 2399 (1996)
  62. Negative “bend resistance” of a ballistic junction: PRB 46, 9648 (1992)
  63. Single electron tunneling by capacitance spectroscopy PRL 68, 3088 (1992) [Earlier CV experiment in 1D: PRL 59, 2802 (1987)
  64. Single electron transistor by tunneling spectroscopy JJAP 36, 3917_1997, PRL 77, 3613 (1996)
  65. Recent review of SET in Rep. Prog. Phys. 64, 701 (2001)
  66. Simulation of the diamond chart JAP 62, 3036 (1987)
  67. Using a QPC to detect the last electron: PRL 70, 1311 (1993), and vandersypen.pdf
  68. Double dot SET: PRB 51, 13872 (1995)
  69. Photoluminescence off a single quantum dot PRL 83, 6252 (1999)
  70. Y-channel transistor: Ysym.mpeg, Ybias.mpeg
  71. Single photon source: viewgraph_set, introduction, PRB 65, 073310 (2002), Science 295, 102 (2002)

 

Presentation topics:

 

To be discussed.

 

Misc. link:

 

Zincblende structure:

http://home3.netcarrier.com/~chan/SOLIDSTATE/CRYSTAL/zincblende.html

Zincblende 111A and 111B structure

http://cst-www.nrl.navy.mil/lattice/struk.jmol/b3.html

Quantum 1D harmonic oscillator:

http://hyperphysics.phy-astr.gsu.edu/hbase/quantum/hosc2.html#c1

Resistance standard using the integer quantum Hall effect: http://www.mintl.com/documents/qhr_000.pdf

http://www.lne.fr/en/r_and_d/electrical_metrology/quantum_hall_effect_ehq.shtml

 

 

 

Progress:

9/1/05: Bulk semiconductor, Kronig-Penny model, origin of energy “band,” bandgap, effective mass…

9/6/05: Bloch theorem, matrix representation of quantum mechanics, tight-binding calculation, 10 by 10 matrix

9/8/05: k*p theory, effective mass theory, wave packet picture that links the quantum mechanical theory to the classical particle-like electron transport, basic transport theory

9/13/05: shallow donor/acceptor theory, semiconductor statistics

9/15/05: device equations, electrostatics, current continuity

9/20/05: origin of heterojunction bandgap alignment

9/22/05: Esaki’s double barrier tunneling diode, transmission peaks, etc.

9/27/05: Esaki’s transfer matrix method, applied to solve a quantum state problem

9/29/05: two systems of “two-dimensional electron gas” --- silicon MOS capacitor and GaAs “HEMT” strucutures; calculation for the band bending, based on a lot of physical assumptions and material parameters

10/4/05: conductivity derived by quantum picture

10/6/05: conductivity, Landau levels in 2D and 3D, experimental evidence of the quantized density of states under magnetic field

10/11/05: Landau level degeneracy, cyclotron resonance set up, capacitance spectroscopy

10/13: transport, screening (electrostatic and dynamic), and calculation of the temperature dependence of mobility

10/18: calculation of the elastic mean free path in Si MOS and GaAs HEMT, quantum picture of the QPC, interpretation of the non-integer transmission, magnetic focusing

10/20: begin to understand the quantum Hall effect; go back to the 2D Landau levels --- consider the boundary of the sample

10/25: Landau levels and QHE

10/27: QHE explained by using the edge currents; Aharonov-Bohm effect in metals and semiconductors

11/2: Aharonov-Bohm interference derivation

11/4: Buttiker formula for a multiple lead ballistic junction

11/8: Single barrier, single electron tunneling, weak localization and universal conductance fluctuation

11/10: Spin-orbit effect, experiments in semiconductors (particularly InAs QWs)

11/17: Single electron transistor, theory and experiments

11/22: SET: verification of “the last electron” and Capacitance Spectroscopy

11/29: Hot electron transistor, Quantum wave transistor

12/1: Other application of quantum phenomena: quantum encryption

12/2: continue

…quantum computing