Peculiarities of photoluminescence of vertical n +/n-GaAs/Al0.25Ga0.75As MBE- and MOCVD-grown structures designed for microwave detectors

Abstract

Vertical MBE- and MOCVD-grown $${n}^{+}/{n}\hbox {-GaAs}/\hbox {Al}_{0.25}\hbox {Ga}_{0.75}\hbox {As}$$ structures used for microwave electronics have been studied with continuous wave and time-correlated single photon counting dynamic photoluminescence technique. The photoluminescence spectra and light emission lifetimes are used to explain the recombination mechanisms of the excited carriers. This paper presents results showing the differences in recombination characteristics of $${n}^{+}\hbox {-Al}_{0.25}\hbox {Ga}_{0.75}\hbox {As}$$ layers grown using MBE process compared with MOCVD process. One of these differences is that the PL spectrum of the MOCVD-grown layer is shifted towards the forbidden energy gap region, as well as the characteristic recombination time is longer than for the MBE-grown sample. This peculiarity can be attributed to the formation of the localised band tails in the $${n}^{+}\hbox {-Al}_{0.25}\hbox {Ga}_{0.75}\hbox {As}$$ MOCVD-grown sample. The proposed analytical model explains the differences in microwave detection properties of the samples grown by MBE and MOCVD processes.