Studies on lattice-mismatched III-V compound semiconductors and pseudomorphic strained resonant tunneling diodes

Focusing on the subject of lattice-mismatched heterostructures, this dissertation is composed of two major parts: (I) Lattice-Mismatched III-V Compound Semiconductors and (II) Pseudomorphic Strained Resonant Tunneling Diodes.; The first part deals with structural and electrical characteristics of lattice-mismatched heteroepitaxial interface, such as GaInAs/GaAs and GaAsP/GaAs. In-plane mismatch was introduced by intentionally changing the epilayer thickness and the composition of sub-host material. Structural characteristics have been studied using double crystal x-ray rocking curve technique, optical beam induced current mapping technique, and Nomarski interference micrograph. Electrical characteristics have been studied using I-V-T, C-V at different frequencies, admittance spectroscopy, and DLTS. Interface charged states and traps which are introduced by a different amount of the lattice-mismatch are discussed with the corresponding structural characterizations. Thermal effects on GaInAs/GaAs heterostructures have been also studied.; In the second part of this dissertation, resonant tunneling structures with pseudomorphic strained emitter spacer have been studied. Lower energy bandgap GaInAs emitter spacer was employed in AlAs/GaAs/AlAs double barrier resonant tunneling structures to improve the diode characteristics and to investigate the role of strained layer. The effects of GaInAs emitter spacer on the characteristics of resonant tunneling diodes are discussed. Experimental data show that peak current density and peak-to-valley ratio are systematically increased, as the indium composition increases. According to a self-consistent I-V simulation, which is based on the quantum mechanical calculation coupled with Thomas-Fermi screening approximation, peak current density, peak-to-valley ratio, and peak voltage are increased as the number of resonant tunneling electrons increase. Current bistability is another important issue on resonant tunneling devices. Based on the experimentally observed current bistability, intrinsic and extrinsic bistability have been studied in detail using the self-consistent calculation and a RLC circuit simulation. (Abstract shortened with permission of author.)...