Anomalous conduction band density of states in Al xGa 1-xAs alloys

Abstract

Temperature dependences of Hall carrier concentration and persistent photoconductivity effects are measured for Al xGa 1-xAs alloys with the AlAs compositional range, 0.26 ≤ x ≤ 0.36. The anomalous conduction band density of states is introduced for the reasonable analysis as Schubert et al. (Phys. Rev. B 30 , 7021 (1984)) previously pointed out. For the first time, the quantitative data for this anomaly are presented for the various AlAs compositions (0.26 ≤ x ≤ 0.36). To explain this anomaly, the three possible explanations originally proposed by Schubert et al. are examined. Their third explanation is the most plausible in which the carrier heating and valley transfer occurs by the internal field. Their third explanation agrees at least qualitatively or semi-quantitatively with our results.