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

Abstract

In this paper, a epitaxial design of InAlN/AlN/InGaN/GaN high electron mobility transistors (HEMTs), considering the vital aspects related to its device exploration is proposed. Mobility of two dimensional electron gas in the proposed, practically viable structures of InxGa1−xN‐channel (0.1 < x < 0.4) HEMT is estimated. It is shown that 2DEG mobility is predominantly limited by alloy scattering rather than phonon scattering, unlike in conventional GaN‐channel HEMTs. Finally, room temperature mobility of 2DEG in InGaN‐channel HEMT is simulated on the basis of alloy scattering and phonon scattering only. Results are in close proximity with reported experimental results. We observe that, for ns ≈ 2 × 1013 cm−2, mobility drops rapidly from ≈900 to ≈550 cm2 V−1 · s−1 as ‘x’ is increased from 0.1 to 0.2 and thereafter it decreases at a relatively lesser rate. Severe degradation in mobility is predicted for x > 0.3.

Very High Density (>1014 cm−2) Polarization‐Induced 2D Hole Gases Observed in Undoped Pseudomorphic InGaN/AlN Heterostructures

“…Interestingly, this potential is lower than the U AL ≈ 1.68 eV for electrons in InGaN. [ 32 ] This is physically expected since the effect of Ga by In cation substitution has a lower effect on the p‐orbital like valence bands which primarily from the N atoms, than the s‐orbital like conduction bands. If Ω 0 ( x ) is considered to be the effective volume Ga or In cation occupies in the unit cell as , then U AL = 1.9 eV results in the best fit to the experimental data.…”

“…U AL for an alloy is typically extracted by fitting to experimental data. Effect of alloy disorder scattering on electrons has previously been investigated in III-nitride semiconductors, both for 2D electrons in AlGaN [30] and InGaN channels, [31,32] and bulk polarization-doped graded structures. [33] Similar investigations of alloy scattering of holes have not yet been reported.…”

Modeling charge density in AlGaN/AlN/InGaN/GaN-based double heterostructures including InGaN layer strain relaxation

“…In spite of some minor deviations that can be related to experimental uncertainties, the proposed model is able to match the available experimental results well. Being generic in nature, this model also applies to InAlN/InGaN/GaN heterostructure designs [36][37][38][39]. This is because the surface state parameters of an InAlN barrier layer is already available [40].…”

Optical characterization of InAlN/AlN/InGaN/GaN/sapphire high electron mobility transistor structures

“…[5] In order to fully exploit these attributes, optimum incorporation of indium into the layer is very crucial. [6] However, several issues pertaining to the epitaxial growth of InGaN have stymied the potential of InGaN based HEMT devices. Large lattice mismatch in InN and GaN, phase segregation, compositional inhomogeneities are some of the major bottlenecks which have limited the operational capabilities of InGaN based devices.…”