Some Studies on a Quantum Well Indium(0.53) Gallium(0.47)-Arsenide/Indium(0.52) Aluminum(0.48) Arsenide Quasi-Misfet.

This dissertation reports the investigation on a novel InGaAs/InAlAs quasi-MISFET in which an inverted modulation doped single quantum well forms the channel and an undoped semi-insulating InAlAs constitutes the gate barrier. The entire structure is grown lattice-matched to InP continuously by molecular beam epitaxy in a single step. Rapid thermal annealing of implanted semiconductors and ohmic contacts has been investigated and has been successfully used in the fabrication of the MISFETs. Charge control modeling of the proposed device predicts the carrier concentration in the channel region fairly well at room temperature, but a quantum mechanical modeling is essential for predicting device behavior at low temperatures. The thickness of the InAlAs doping layer is found to be an important parameter which controls the device turn-on characteristics. The properties of rapid thermal annealed III-V compounds have been investigated in detail. Normal InGaAs/InAlAs modulation-doped structures show sharp decreases in sheet electron concentration and in electron mobility for annealing temperatures higher than 750(DEGREES)C, while this trend is smaller in the inverted structures. Si-implantation and rapid thermal annealing is found to be a suitable process for the fabrication of high-performance self-aligned gate InGaAs/InAlAs heterostructure devices. Interdiffusion and wavelength modification phenomenon by heat treatment have been investigated for the first time in InGaAs/InAlAs heterostructures. Fairly high electron mobilities are measured for single quantum well MISFET structures even with well thicknesses as small as 100 (ANGSTROM). The InAlAs gate barrier is effective in reducing the gate leakage current. Gate leakage currents are reduced further with a composite dielectric consisting of oxidized Al and InAlAs. Rapid thermal annealing of layered contact metals including Ti yields a contact resistance as low as 0.1 (OMEGA)-mm. Improved device performance is obtained with this ohmic contact and an extrinsic transconductance of 310 mS/mm is measured in a 1.0 (mu)m gate device at 300 K. A cut-off frequency of 32 GHz, measured in a 1.0 (mu)m device, is the best obtained so far with this material system.Ph.D.Electrical engineeringUniversity of Michiganhttp://deepblue.lib.umich.edu/bitstream/2027.42/161456/1/8712205.pd