Determination of conduction band tail and Fermi energy of heavily Si-doped GaAs by room-temperature photoluminescence

A line-shape analysis of room temperature photoluminescence (PL) spectra was carried out on Si-doped GaAs samples grown by molecular beam epitaxy. The electron concentration n of the samples ranges from 1.0×1017 to 4.2×1018 cm−3. It was found that the conduction band tail ηc and the Fermi energy εf measured from the conduction band minimum can be expressed as ηc=2.0×10−8n1/3(eV) and εf=−0.074+1.03×10−7n1/3(eV), respectively. The PL peak energy, at which the electron concentration per unit energy in the conduction band is maximum, can also be expressed as 1.426+2.4×10−14n2/3(eV).