Heavily Si-doped GaAs grown by metalorganic chemical vapor deposition

Heavily Si-doped GaAs layers were grown by a metalorganic chemical vapor deposition method using disilane (Si₂H₆) as a silicon dopant source gas. The grown layers were characterized by the van der Pauw, secondary ion mass spectroscopy, and low-temperature Fourier transformation infrared spectroscopy (FTIR) method. The carrier concentration has no growth temperature dependence from 550 to 700 °C temperature range. However, it has temperature dependence below 550 °C and above 700 °C. The carrier concentration of Si-doped GaAs is usually saturated at 6×10 ¹⁸ cm^-3 level. Further, Si doping makes the carrier concentration decrease. By using the low-temperature FTIR method, absorption bands for Si_Ga, Si_As, Si _Ga-Si_As pair, and lower energy bands (374 and 369 cm ^-1) were observed in heavily Si-doped GaAs. The peak intensity for Si_Ga is smaller than that for Si_As, and the peak heights at 374 and 369 cm^-1 are relatively larger than that for the other peaks. These facts suggest that, in heavily Si-doped GaAs, a part of Si_Ga formed Si_Ga related defects, which act as new donor centers.