Reading Worksheet Class 15 Physics 585Please complete bring to class on Thursday. We will use it to guide discussion you will hand it in later. Name______

Your QUESTIONS are important. WRITE down at least two you have. Also put star by the items of greatest misunderstanding.

Class 15: Ohring Chapter 8Epitaxy through end of8.3, pages 417- 438.

Look at and understand all of the figures in chapter. We are going to go fast over the material, emphasizing concepts, with few derivations etc. and not even all of the figures.

8.1. Introduction 417

  1. Learn terms: homoepitaxy, heteroepitaxy, strained-layer, relaxed, pseudomorphic, layer-film epitaxy. Also note: lateral growth, superlattice, and quantum wells.

8.2. Manifestations of Epitaxy: 8.2.1 Introduction 8.2.2 Graphoepitaxy 420

  1. Graphoepitaxy: Could you explain figure 8.3 to a friend?
  2. What is it that Machlin argued?

Heteroepitaxy8.2.3.1 Crystallographic Notation

  1. Learn how to read the tetrad of numbers in the examples. Write some down. Can you make sense of the direction arrows on figure 8-4?
  1. Misfits again: do you have compassion on the misfits? 

8.2.3.2 Geometrical Features of Metal/Semiconductor Heteroepitaxy;

8.2.3.2.1 Metal/Silicon

8.2.3.2.2 -FeSi2/Silicon

8.2.3.2.3 Metal-GaAs Heteroepitaxy

  1. What metals, and metallic compounds can be grown epitaxially on GaAs?
  2. What orientation?

8.2.4 Tilted-Layer Epitaxy

  1. Do you wish that the term “vicinal” were defined?
  2. Look at the terraces in the substrate crystal in figure 8-6 (top). The substrate is the one will straight lines. It was cut slightly off parallel.

8.3. Lattice Misfit and Defects in Epitaxial Films.429

8.3.1Equilibrium Theory of Lattice Misfit

  1. What is dc? Finding it is a major activity of this section (8.3). Pay attention to the discussion but you don’t have to understand the derivation of each term in 8-4. Instead see what they are about. The last 2 paragraphs have the take home message. And lead to next section,

8.3.2 Defects in GexSi1-x/Si Films

  1. The lattice parameter of Ge is 4% larger than that of Si. Use this to understand figure 8-8.
  2. w is a new parameter. It is used in eqn. 8-6 to calculate dc.
  3. Look at the figures 8-9. It is about “surface roughening”.

8.3.3 Types and Sources of Defects in Epitaxial Films

  1. Figure 8-10 is your friend. Can you explain each type or defects? You will soon. Read all, and understand, especially the first two.

8.3.3.1 Defect Propagation from Substrate, 8.3.3.2 Stacking Faults, 8.3.3.3 Dislocation Loops from Precipitates, Impurities, or Dopants, and 8.3.3.4 Low-Angle Grain Boundaries and Twins

8.3.4 Formation of Misfit Dislocations and 8.3.5 Epitaxial Defects in Perspective

  1. If a film grows by SK or island is it likely to have the perfection of a bulk crystal?

8.4 Epitaxy of Compound Semiconductors439

8.4.1 Introduction

8.4.2 Compound-Semiconductor Materials

8.4.2.1 Properties

8.4.2.1.1 Direct and Indirect Energy Bandgaps

8.4.2.1.2 Bandgap Energy

8.4.2.1.3 Lattice Parameter

8.4.2.1.4 Thermal Expansion Coefficient

8.4.2.2 Designing Epitaxial Film-Substrate Combinations

8.4.3 Scope of Devices and Applications

8.4.4 Lighting the IR to Visible Spectrum with Compound Semiconductors

8.4.4.1 Optical Communications

8.4.4.2 Light-Emitting Semiconductor Devices

8.4.4.3 GaN Light-Emitting Semiconductor Devices

8.5. High-Temperature Methods for Depositing EpitaxialSemiconductor Films. . 453

8.5.1 Scope

8.5.2 Epitaxial Films from Melts

8.5.2.1 Liquid-Phase Epitaxy

8.5.2.2 Seeded Lateral Epitaxial Film Growth over Insulators

8.5.3 CVD-Based Epitaxy

8.5.3.1 Metalorganic CVD Processes for Semiconductor Epitaxy

8.5.3.1.1 Precursors

8.5.3.1.2 Gas Reactions

8.5.3.1.3 Reactors

8.5.3.1.4 Film Growth Rate

8.5.3.2 Atomic Layer Epitaxy (ALE)

8.5.3.3 Additional CVD Epitaxy Processes

8.6. Low-Temperature Methods for Depositing Epitaxial Semiconductor Films.466

8.6.1 Scope

8.6.2 Molecular Bean Epitaxy

8.6.2.1 Gas Source MBE

8.6.2.2 MBE vs OMVPE: Advantages and Disadvantages

8.6.3 Silicon Heteroepitaxy

8.6.3.1 Wafer Bonding

8.6.3.2 Ultrahigh-Vacuum Chemical-Vapor Deposition (UHV/CVD)

8.6.4 Less Common Epitaxy Processes

8.6.4.1 Molecular Beam Allotaxy (MBA)

8.6.4.2 Mesotaxy

8.6.4.3 van der Waals Epitaxy

8.6.4.4 Colloidal Epitaxy

8.7. Mechanisms and Characterization of Epitaxial Film Growth ...... 476

8.7.1 Homoepitaxy of Silicon

8.7.2 Film Growth of GaAs and Related Films

8.7.2.1 Kinetics of Adsorption and Desorption

8.7.2.2 Mechanisms

8.7.2.3 Stabilized and Reconstructed Surfaces

8.7.2.4 Mechanism of Growth in GaInAsP

8.7.3 Selective Epitaxy

8.7.3.1 Selective Epitaxy in Silicon Materials

8.7.3.2 Selective Epitaxy in Compound Semiconductors

8.7.3.2.1 MBE

8.7.3.2.2 MOCVD

8.7.3.2.3 MOMBE

8.7.4 In Situ Film Characterization of MBE Films

8.7.4.1 LEED

8.7.4.2 RHEED

8.7.4.3 RHEED Oscillations

8.8. Conclusion ...... 488