Investigations of Deep Level Defects in Semiconductor Material Systems

Abstract

In this thesis, we present the results of two groups of investigations of deep level defects in semiconductor material systems. Chapter 1 consists of an overview of the thesis, background information on semiconductor impurities, and a description of deep level transient spectroscopy (DLTS). Chapter 2 contains discussions of the experiments performed on transition metal silicide-silicon Schottky barrier structures to probe for the existence of deep levels. We investigated platinum, palladium, and nickel silicides on n-type silicon which were annealed at temperatures from 300 to 800°C. The primary techniques used were DLTS, current-voltage (IV), and capacitance-voltage (C-V) measurements for electronic characterizations, and Rutherford backscattering spectrometry (RBS) to determine the silicide phase and film condition. For our samples, 700°C was the maximum temperature below which no significant degradation of the barrier or contamination of the underlying silicon were observed in platinum and palladium silicide structures. Nickel silicide structures could only withstand temperatures up to 500°C. Cobalt, chromium, and erbium silicides were also studied using DLTS. These measurements constitute the first series of studies of deep level contamination of the silicon underlying a transition metal suicide thin film. Chapter 3 details our DLTS studies of four different compositions of the alloy In1-xGaxAsyP1-y. Our samples, with bandgaps of 0.75, 0.83, 0.95,and 1.1 eV, covered the range of compositions that are lattice-matched to InP and are used for long-wavelength optoelectronic devices. No traps were observed above the detection limit of 5 x 1013 cm-3. The only exception was one sample, which had a trap that was attributed to a lattice defect in the substrate. These DLTS experiments were the first attempt to investigate deep level defects in In1-xGaxAsyP1-y.