Measurement of the concentration of 2D electrons in δ-doped InGaAs/GaAs pseudomorphic transistor structures using the photoluminescence spectroscopy

Concentration of 2D electrons n s is measured in the modulation-doped PHEMT structures with the aid of two photoluminescence (PL) methods using halfwidth of the 1e-1hh band and the energy difference E F-E 1e in the experimental PL spectra. The applicability of the methods is analyzed, and a method for the determination of energy E F from the temperature dependence of the intensity ratio of the 2e-1hh and 1e-1hh bands is proposed. It is demonstrated that concentrations n s are in good agreement with the results of the Hall-effect measurements at relatively low concentrations (n s ≤ 2.5 × 1012) when the parallel conduction along the δ layer is absent. At stronger doping, the PL methods yield more accurate concentrations n s .