Electronic transport in n- and p-type modulation dopedGaxIn1−xNyAs1−y/ GaAs quantum wells

Abstract

We present a comprehensive study of longitudinal transport oftwo-dimensional (2D) carriers in n- and p-type modulation dopedGaxIn1−xNyAs1−y /GaAs quantum well structures. The Hall mobility and carrier density of electrons in then-modulation doped quantum wells (QWs) decreases with increasing nitrogen composition.However, the mobility of the 2D holes in p-modulation doped wells is not influenced bynitrogen and it is significantly higher than that of 2D electrons in n-modulation dopedmaterial. The observed behaviour is explained in terms of increasing electron effective massas well as enhanced N-related alloying scattering with increasing nitrogen content.In order to determine the conduction band (CB) and valence band (VB) structures as wellas electron and hole effective masses, the band anticrossing model with an eight-band approximation in the Lüttinger–Kohn approach is used. The effects of strain, quantumconfinement and the strong coupling between the localized nitrogen states and the CBextended states of GaInAs are considered in the calculations. The results indicate that thenitrogen induces a strong perturbation to the CB of the matrix semiconductor whilst theVB remains unaffected.The temperature dependent mobility of 2D electron gas is discussed using an analyticalmodel that accounts for the most important scattering mechanisms. The results indicatethat the interface roughness and N-related alloy scattering are the dominant mechanisms atlow temperatures, while polar optical phonon and N-related alloy scattering limit mobilityat high temperatures.