Electronic transport in n- and p-type modulation doped Ga_xIn_1−xN_yAs_1−y/GaAs quantum wells

Abstract

We present a comprehensive study of longitudinal transport of two-dimensional (2D) carriers in n- and p-type modulation doped Ga(x)In(1-x)N(y)As(1-y) /GaAs quantum well structures. The Hall mobility and carrier density of electrons in the n-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 by nitrogen and it is significantly higher than that of 2D electrons in n-modulation doped material. The observed behaviour is explained in terms of increasing electron effective mass as 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 well as electron and hole effective masses, the band anticrossing model with an eight-band [Formula: see text] approximation in the Lüttinger-Kohn approach is used. The effects of strain, quantum confinement and the strong coupling between the localized nitrogen states and the CB extended states of GaInAs are considered in the calculations. The results indicate that the nitrogen induces a strong perturbation to the CB of the matrix semiconductor whilst the VB remains unaffected. The temperature dependent mobility of 2D electron gas is discussed using an analytical model that accounts for the most important scattering mechanisms. The results indicate that the interface roughness and N-related alloy scattering are the dominant mechanisms at low temperatures, while polar optical phonon and N-related alloy scattering limit mobility at high temperatures.

The role of dislocation-induced scattering in electronic transport in GaxIn1-xN alloys

“…However, for the sample with the lowest Ga concentration, Ga 0.06 In 0.94  N, it decreases from 1,035 to 890 cm 2 /Vs with increasing temperature from 100 to 300 K but does not show any significant change in the other two samples, which is a characteristic feature of metallic-like semiconductors [7,26,27]. The insensitivity of carrier mobility to temperature is commonly observed in polar materials with elevated carrier densities where the polar interactions are screened [19,25,29-33]. …”

“…At high temperatures, however, interface roughness and alloy potential restrict the mobility, but effect of the dislocation scattering becomes less dominant as a result of shortening Debye screening length due to higher carrier density. Furthermore, in the high-carrier-concentration regime, electron–phonon scattering is heavily screened, as described above and in references [19,25,29-33]. …”

Magnetotransport study on as-grown and annealed n- and p-type modulation-doped GaInNAs/GaAs strained quantum well structures

“…On the contrary, in the presence of the nitrogen, it has been theoretically demonstrated that hole effective mass and hole mobility remain unaffected [14-16]. So far, much effort has been focused on nitrogen dependence of electron effective mass and electron mobility, ignoring the composition dependence of hole effective mass and hole mobility.…”

Energy and momentum relaxation dynamics of hot holes in modulation doped GaInNAs/GaAs quantum wells

“…Therefore, in material with relatively high nitrogen incorporation, the hole mobility can be higher than the electron mobility at low temperature because of both smaller effective mass and the lack of scattering by nitrogen complexes as observed in our previous studies. 16,17 The high hole mobility provides the motivation for the current work, i.e., to establish a full understanding of hole transport, particularly at high electric field for their potential application in ultrafast novel devices.…”