Epitaxial Growth of (SiC)_XGe_1-x on Silicon Substrates

Abstract

Silicon carbide (SiC) has recently been used to form high intensity, blue-light emitting diodes (1) and high temperature electronic devices (2). SiC’s physical and chemical properties, (e.g., energy bandgap and dielectric constant) have filled an important materials void, offering semiconductor devices that can operate under extreme environmental conditions. In this paper, we report on chemical vapor deposition (CVD) growth of (SiC)_x Ge_1-x single crystal films on silicon substrates. The silicon carbide germanium (SiC)_X Ge_1-x ternary system has only been studied in some detail by D. Girginoudi and co-workers (3). These researchers reported on the growth of amorphous (SiC)_x Ge_1-x films by RF sputtering. In the present study, epitaxial growth of (SiC)_x Ge_1-x on silicon substrates was performed using a CVD reactor which employed SiH₄, C₃H₈, GeH₄, and H₂. A detailed description of the CVD reactor system is given in reference 4. The silicon samples (001) were on- and off-axis (2° toward <110> direction). The substrates were etched using HF: de-ionized water after a standard cleaning to remove any surface oxide layers. Epitaxial growth took place at approximately 1370°C with H₂ as the carrier gas. The Ge/Si ratio in the gas flow phase was varied from 0.05 to 0.20. Under these conditions, the growth rate was approximately 1.5 μm/hour.