Growth and characterization of novel silicon-based heterostructures and device applications

We have demonstrated the metastability enhancement of the epitaxial growth on reduced area by selective epitaxial growth of SiGe on patterned Si substrates. A quantitative model of the effect of the selective growth on dislocation density has been developed and compared to experiments. It was concluded that the dominant dislocation nucleation source in the selective areas occurred at the specific heterogeneous sites at the edges of selective areas. This edge nucleation can be controlled by adjusting the orientation of the sidewalls.; We have investigated the reduction of threading dislocation density by graded relaxed buffers and strained layer superlattices. The threading dislocation densities of the completely relaxed films were on the order of 10{dollar}sp7{dollar}cm{dollar}sp{lcub}-2{rcub}{dollar}, on which the electron modulation doped structures and the electron resonant tunneling diodes have been successfully fabricated. We also measured the electron effective mass of tensile SiGe on Si for the first time.; We have studied the first chemical vapor deposition growth of strained Si{dollar}rmsb{lcub}1-x{rcub}Gesb{lcub}x{rcub}{dollar} alloy layers on {dollar}langle{dollar}110{dollar}rangle{dollar} Si substrates. Compared to the same growth conditions on {dollar}langle{dollar}100{dollar}rangle{dollar} substrates, a slightly lower Ge composition, but a much lower growth rate was observed. From photoluminescence measurements, the bandgap of these films for 0.16 {dollar}le{dollar} x {dollar}le{dollar} 0.43 was determined for the first time, and compared to theory. The conduction band offset was evaluated by the well width dependence of no-phonon luminescence process for the first time.; We have investigated the growth of 3C SiC on Si at the growth temperature from 700 to 1100{dollar}spcirc{dollar}C, using a single precursor (methylsilane) without any carbonization step. An optimum growth window was found at 800{dollar}spcirc{dollar}C and a "two-step" growth technique was utilized to improve the crystalline quality of the high temperature growth. A positive temperature coefficient of breakdown voltage of Schottky barriers on 3C SiC was observed for the first time. Simple Pt-Schottky barriers fabricated on n-type SiC on Si exhibited a hard breakdown at 60 V.; We have successfully fabricated single crystalline SiGeC random alloys with carbon concentration as high as 1.6%. The growth with dichlorosilane as a silicon source was more favorable than the silane source in terms of incorporating a large amount of substitutional carbon. The Fourier Transform Infrared Spectroscopy of these alloys exhibited a substitutional carbon at 600 cm{dollar}sp{lcub}-1{rcub}{dollar}, with no indication of silicon carbide precipitation.