Terahertz emission in GaAs grown on Si(100) at different substrate temperatures
Terahertz (THz) emission in gallium arsenide grown on silicon (GaAs on Si) at different substrate temperatures, Ts = 320oC, 520oC and 630oC, is presented in this study. An LTG-GaAs buffer layer system was implemented to compensate for the ~4.1% lattice mismatch in the heteroepitaxy of GaAs on Si(100) by molecular beam epitaxy. X-ray results confirmed the high crystalline quality of the GaAs epitaxial layers on Si. The GaAs crystal quality improved with increasing Si substrate temperature. The THz emission of GaAs on Si grown at Ts = 520oC, measured by THz time-domain spectroscopy in reflection geometry, exhibited the highest THz intensity despite not having the highest crystalline quality. The THz emission efficiency was dependent on the Si substrate temperature. Additionally, for LTG-GaAs on Si grown at Ts = 320oC, the THz emission was comparable to LTG-GaAs grown on semi-insulating GaAs (SI-GaAs). For GaAs on Si grown at Ts = 630oC, the THz emission was significantly higher than GaAs on SI-GaAs. The heteroepitaxy of GaAs on Si proved effective in enhancing the THz emission.