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

Abstract

We report the observation of thermal annealing- and nitrogen-induced effects on electronic transport properties of as-grown and annealed n- and p-type modulation-doped Ga1 - xInxNyAs1 - y (x = 0.32, y = 0, 0.009, and 0.012) strained quantum well (QW) structures using magnetotransport measurements. Strong and well-resolved Shubnikov de Haas (SdH) oscillations are observed at magnetic fields as low as 3 T and persist to temperatures as high as 20 K, which are used to determine effective mass, 2D carrier density, and Fermi energy. The analysis of temperature dependence of SdH oscillations revealed that the electron mass enhances with increasing nitrogen content. Furthermore, even the current theory of dilute nitrides does not predict a change in hole effective mass; nitrogen dependency of hole effective mass is found and attributed to both strain- and confinement-induced effects on the valence band. Both electron and hole effective masses are changed after thermal annealing process. Although all samples were doped with the same density, the presence of nitrogen in n-type material gives rise to an enhancement in the 2D electron density compared to the 2D hole density as a result of enhanced effective mass due to the effect of nitrogen on conduction band. Our results reveal that effective mass and 2D carrier density can be tailored by nitrogen composition and thermal annealing-induced effects.PACS72.00.00; 72.15.Gd; 72.80.Ey

Electronic transport in n-type modulation-doped AlGaAs/GaAsBi quantum well structures: influence of Bi and thermal annealing on electron effective mass and electron mobility

“…The oscillatory part of magnetoresistance measurements (SdH oscillations) as a function of magnetic field and temperature is expressed as [39][40][41]…”

“…The effect of background magnetoresistance should be excluded to analyse observed SdH oscillations. Two methods are employed to exclude the effect of background: (i) taking the negative second derivative of the magnetoresistance data with respect to the magnetic field or (ii) fitting the magnetoresistance data with a second-degree polynomial [39][40][41]. We have used the first method to remove the effect of background magnetoresistance.…”

“…It is clear from figure 4 that the amplitude of the SdH oscillations decreases with increasing temperature. This characteristic allows determining the electron effective mass [39,41,42]. The thermal damping of the SdH oscillations at a fixed magnetic field is expressed in terms of temperature, magnetic field, and effective mass using equations In-plane electron effective mass is determined by analysing the SdH oscillations as a function of temperature between 4.2 and 60 K. The relation between amplitudes of oscillations A(Т 1 ) and A(Т 2 ) are determined at temperatures Т 1 and Т 2 (Т 1 >Т 2 ) at the same value of the magnetic field.…”

The effect of barrier layers on 2D electron effective mass in Al0.3Ga0.7N/AlN/GaN heterostructures

“…On the other hand, this ratio slightly decreases when doping is added to the sample with the spacer layer. The damping of SdH oscillation' amplitude with the temperature at a fixed magnetic field is a very reliable technique to determine carrier effective mass [23,30,[39][40][41][42][43][44]. The relative changes in SdH oscillations amplitude are given by [21][22][23][24],…”

Nitrogen induced localised-state ensemble effect on multi quantum well GaInNAs with low indium concentration

“…GaInNAs/GaAs has a much larger conduction band offset due to the decreased curvature of the new conduction band in dilute nitrides [3]. This consequently increases the electron effective mass [4]. With a deeper quantum well (QW) and increment of electron mass, GaInNAs provides better confinement of the carriers in the quantised sub-band and a better match of the valence band and conduction band densities of states.…”