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

Abstract

Electronic transport in unintentionally doped GaxIn1-xN alloys with various Ga concentrations (x = 0.06, 0.32 and 0.52) is studied. Hall effect measurements are performed at temperatures between 77 and 300 K. Temperature dependence of carrier mobility is analysed by an analytical formula based on two-dimensional degenerate statistics by taking into account all major scattering mechanisms for a two-dimensional electron gas confined in a triangular quantum well between GaxIn1-xN epilayer and GaN buffer. Experimental results show that as the Ga concentration increases, mobility not only decreases drastically but also becomes less temperature dependent. Carrier density is almost temperature independent and tends to increase with increasing Ga concentration. The weak temperature dependence of the mobility may be attributed to screening of polar optical phonon scattering at high temperatures by the high free carrier concentration, which is at the order of 1014 cm−2. In our analytical model, the dislocation density is used as an adjustable parameter for the best fit to the experimental results. Our results reveal that in the samples with lower Ga compositions and carrier concentrations, alloy and interface roughness scattering are the dominant scattering mechanisms at low temperatures, while at high temperatures, optical phonon scattering is the dominant mechanism. In the samples with higher Ga compositions and carrier concentrations, however, dislocation scattering becomes more significant and suppresses the effect of longitudinal optical phonon scattering at high temperatures, leading to an almost temperature-independent behaviour.

Power Loss Mechanisms in Indium-Rich InGaN Samples

“…20,23 The mobility was also independent of temperature for these structures. 20 This behavior can be explained by decreased dislocation scattering. The electron mobility also decreased with In concentration from 0.1 to 0.4 in In x Ga 1Àx N. 21,22 Figure 4 shows the indium mole fraction dependence of the power loss per carrier as determined from Fig.…”

“…Electronic transport properties of In x Ga 1Àx N structures with different In concentrations have been studied by many research groups. [20][21][22][23] It has been found that the electron mobility increases with increasing In concentration from 0.48 to 0.94 in In x Ga 1Àx N structures. 20,23 The mobility was also independent of temperature for these structures.…”

“…[20][21][22][23] It has been found that the electron mobility increases with increasing In concentration from 0.48 to 0.94 in In x Ga 1Àx N structures. 20,23 The mobility was also independent of temperature for these structures. 20 This behavior can be explained by decreased dislocation scattering.…”

Aspects of Epitaxial Design and Estimation of 2DEG Mobility in InAlN/AlN/InGaN/GaN High Electron Mobility Transistors

“…, ω 0 is optical phonon frequency and G k 0 [24,25] To estimate the scattering rate, the only parameter required now is the electric field in the channel F 3 . On the basis of electrostatic analysis of the schematic conduction band profile (Figure 1) we arrived at the dependence of electric field F 3 on 2DEG density (n s ) as given by Eq.…”

High-frequency response and thermal effects in GaN diodes and transistors: modeling and experimental characterization

“…Alloy scattering (ternary materials) and dislocation scattering (GaN layer) are also considered as scatterings with defects and they are relevant in our heterostructures [62].…”