Optical determination of carrier density in pseudomorphic AlGaAs/InGaAs/GaAs heterohyphen;fieldhyphen;effect transistor structures by photoluminescence

摘要

A photoluminescence (PL) analysis of a highly degenerate twohyphen;dimensional electron gas (2DEG) in pseudomorphic modulationhyphen;doped AlGaAs/InGaAs/GaAs transistor structures is reported. The PL response from samples with one or two populated electron subbands is dominated by one or two spectral bands, respectively, with a highhyphen;energy intensity cutoff. The spectral width varies linearly with the measured 2DEG sheet densitynsor with a Schottky barrier depletion voltage, which directly reflects the twohyphen;dimensional density of states (2DDOS) below the Fermi level. We used the effective electron mass from cyclotron resonance experiments to evaluate the 2DDOS and can thus directly determinensfrom the spectral width via the 2DDOS. Independentnsvalues were obtained from Shubnikovndash;de Haas measurements and agree excellently withnsvalues from PL.