6.772 | Spring 2003 | Graduate

Compound Semiconductor Devices

Calendar

LEC # TOPICS KEY DATES
1 Compound Semiconductors: The families (III-V’s, II-VI’s, IV-VI’s, IV-IV’s), alloys, Eg vs a; band structures (E vs k; Γ, L, X minima; direct vs. indirect gaps); crystal lattices, electrical properties, optical properties; trends in properties and the periodic table. The useful compounds.

2 Metal-Semiconductor Interfaces (Schottky Barriers): The compound semiconductor surface; Fermi level pinning. Theories of barrier formation and of current flow; diffusive vs. ballistic flow; contrasts with p-n diodes. Theory and practice of ohmic contacts.

3 Heterostructures: E-x Profiles: ΔEc, ΔEv, Ec(x), Ev(x); no(x), po(x); modulation doping. Conduction parallel to heterojunction; mobility in semiconductors and carrier scattering mechanisms. Problem Set 1 Out
4 Heterojunctions: Conduction normal to junction: I-V models and characteristics. Theory of graded layers; creation of internal carrier-specific fields.

5 Quantum Effect Structures: Quantum wells: theory, fabrication, observation (verification), and application. Quantum wires and dots.

6 Quantum Effect Structures (contd.): Coupled quantum structures: super lattices. Resonant tunneling: RTD structure and concept. I-V theory. Related devices and applications: RTD-load logic, memory cells. Problem Set 1 Due
7 Epitaxy: Concerns / constraints — lattice-matched systems; strained layers (pseudomorphic) — limits of thickness; impact of strain on bands, properties.

8 Epitaxy (contd.): Techniques — MOCVD, CBE, MBE (MO, GS, & SS).

Device Processing: Etching. Surface passivation; dielectric films.

Problem Set 2 Out
9 MESFETs: Basic concept, models for terminal characteristics; accounting for velocity saturation. Dynamic models: large signal switching transients; small signal, high f models. Fabrication sequences; application-specific designs (power, digital, low noise microwave).

10 MESFET Digital Logic Families: Performance criteria for logic. Logic families: normally-on logic (FL, BFL, SDFL); normally-off logic (DCFL); comparison offamilies; examples of fabrication sequences; performance data; state-of-the-art commercially.**

Microwave Linear ICs**: Building blocks, amplifier stages, waveguides, lumped elements. MMIC and wireless technologies.

Problem Set 2 Due
11 HFETs (Doped Channel): Concept; I-V model including velocity saturation; gate 2 characteristics; output conductance; applications of strained layers.

HFETs (Intrinsic Gate): HIGFET’s — basic device, features, theory. Complementary structures for logic.

12 HFETs (Modulation Doped): MODFETs — basic device, theory. Deep level problem (transconductance collapse); pseudomorphic solution.  Telecommunications applications — key features: gain, bandwidth, linearly, noise.

13 HBTs: Concept: emitter efficiency, base transport, base resistance, junction capacitance. HJ collector and collector-up refinements. Applications of graded layers: control of HJ spikes; ballistic injection; problems with upper-valley minima. Problem Set 3 Out
14 HBTs (contd.): State-of-the-art commercial HBT technologies (III-V and IV-IV).

15 Light Emission and Absorption: Basic theory. Direct vs. indirect gap. Band-to-band and band-to-impurity transistions. Problem Set 3 Due
16 Dielectric Waveguides / Photonic Crystals: Basics of optical cavities and waveguides. Photonic crystal concepts, structures, issues.

17 Light Emitting Diodes: LEDs — structure, materials, characteristics (i-v, l-i, l-l), performance. Light extraction, current spreading, photon recycling.

18 LEDs (contd.): Applications in displays and illumination — considerations, current practice, recent commercial developments.

19 Laser Diodes: Feedback and stimulated emission. Cavity design; double heterostructure concept. Quantum well, wire, dot active regions. Strained layers; pseudomorphic active regions.

20/21 Laser Diodes (contd.): In-plane lasers: double heterostructure, quantum well, multi-contact, surface emitting. Vertical cavity surface emitting lasers (VCSELs). Modulation and control of emission. New structures and material systems including blue-green lasers and cascade lasers.

22 Detectors: Structure and theory of basic types: p-i-n (conventional and unicarrier), APD, Schottky diode, m-s-m; resonant cavity concepts.

23 Detectors (contd.): Vertical vs. in-plane geometries. Quantum well intersubband photodetectors.

24 Modulators: Multiple quantum well structures, quantum confined Stark effect; SEED. Waveguide couplers, switches, modulators.

Photonic Circuits, Optoelectronic Integrated Circuits (OEICs): Integration goals and challenges; applications.

25 OEICs (contd.): Approaches to integration and current state-of-the-art. Epitaxial stacks, multiple-epitaxial runs, epitaxy on processed electronics (GaAs-on-Si, GaAs-on-GaAs, Si-on-GaAs). Bonding. Hybrid integration. Self-assembly.

26 Quantum Effect Devices: Electron waveguides, single electron transistors, etc.

27 Device Research Conference Preview / Industrial Overview: What’s new and exciting this year in research and in the marketplace?

Course Info

As Taught In
Spring 2003
Level
Learning Resource Types
Lecture Notes
Projects with Examples
Problem Sets with Solutions