Atomic layer epitaxy of gallium arsenide and aluminum gallium arsenide for device applications

Atomic Layer Epitaxy offers ultimate control of the thin film deposition process. ALE allows the placement of individual atomic layers in a controlled, equilibrium fashion. However, the process has suffered from several limitations, among which are background carbon contamination, small substrates, low growth rates, difficulties with ternary alloys and device demonstrations. Therefore, this study addresses these current problems. It is the objective to show the viability of ALE as a next generation deposition technique for optoelectronic devices. This was demonstrated by the development of an ALE deposition system which allows the growth of device quality materials on large area substrates with practical growth rates. Materials grown were then used to fabricate state-of-the-art devices in the GaAs/AlGaAs material systems with performances comparable to or better than existing methods such as MetalOrganic Chemical Vapor Deposition (MOCVD) or Molecular Beam Epitaxy.; ALE of the {dollar}rm Alsb{lcub}x{rcub}Gasb{lcub}1-x{rcub}As{dollar} material system for {dollar}0le{dollar} x {dollar}le1{dollar} has been demonstrated on a specially converted, commercial MOCVD reactor. Short exposure times ({dollar}sim{dollar}0.08-2s) to the reactant gas streams are demonstrated to permit ALE growth of device quality GaAs and AlGaAs over a wide temperature (550 to 650{dollar}spcirc{dollar}C) window and reactant fluxes. ALE growth of device quality GaAs exhibiting the self-limiting effect at a growth rate of 1 and 2{dollar}mu m/hr{dollar} was also achieved. Background carbon doping levels varied from below {dollar}10sp{lcub}15{rcub}{dollar}cm{dollar}sp{lcub}-3{rcub}{dollar} to {dollar}10sp{lcub}20{rcub}{dollar}cm{dollar}sp{lcub}-3{rcub}{dollar} and depended strongly on aluminum content (x), growth temperature and V/III ratio. N-type doping with silane was also performed, achieving doping levels of {dollar}7times 10sp{lcub}18{rcub}{dollar} and {dollar}10sp{lcub}18{rcub}{dollar}cm{dollar}sp{lcub}-3{rcub}{dollar} in GaAs and {dollar}rm Alsb{lcub}0.3{rcub}Gasb{lcub}0.7{rcub}As,{dollar} respectively.; The major achievement attained is the demonstration of state of the art heterojunction devices using the GaAs/AlGaAs materials deposited by entirely ALE. Successful application of the ALE grown material was realized in Heterojunction Bipolar Transistors, delta doped Metal Semiconductor Field Effect Transistors, Resonant Tunneling Diodes (RTD's) and other quantum effect structures. AlGaAs/GaAs quantum wells and RTD's grown wholly by ALE displayed excellent thickness uniformity with submonolayer control of thickness as measured by photoluminescence emissions and by I-V variations, respectively.