Development of Quaternary InAlGaN Barrier Layer for High Electron Mobility Transistor Structures.

Justinas Jorudas,Paweł Prystawko,Jūras Mickevičius,Ramūnas Aleksiejūnas,Paweł Piotr Michałowski,Irmantas Kašalynas,Marcin Kryśko,Artūr Šimukovič

doi:10.3390/ma15031118

Abstract

A quaternary lattice matched InAlGaN barrier layer with am indium content of 16.5 ± 0.2% and thickness of 9 nm was developed for high electron mobility transistor structures using the metalorganic chemical-vapor deposition method. The structural, morphological, optical and electrical properties of the layer were investigated planning realization of microwave power and terahertz plasmonic devices. The measured X-ray diffraction and modeled band diagram characteristics revealed the structural parameters of the grown In0.165Al0.775Ga0.06N/Al0.6Ga0.4N/GaN heterostructure, explaining the origin of barrier photoluminescence peak position at 3.98 eV with the linewidth of 0.2 eV and the expected red-shift of 0.4 eV only. The thermally stable density of the two-dimension electron gas at the depth of 10.5 nm was experimentally confirmed to be 1.2 × 1013 cm−2 (1.6 × 1013 cm−2 in theory) with the low-field mobility values of 1590 cm2/(V·s) and 8830 cm2/(V·s) at the temperatures of 300 K and 77 K, respectively.

Highlights

III-nitride high electron mobility transistor (HEMT) structures based on the AlGaN/GaN heterostructure are extensively used in various applications such as gas sensors [1,2], THz detectors [3,4,5,6] and emitters [7,8], and high-power microwave devices [9,10,11,12]
The amount of these impurities was close to that obtained by the low-frequency noise and THz electroluminescence spectroscopy methods in the AlGaN/GaN HEMT on sapphire [27,29]
A small fraction of Ga was found in the barrier, which occasionally occurs during the growth of the InAlN barrier in metalorganic chemical vapor deposition (MOCVD) reactor [30,31,32]

Summary

Introduction

III-nitride high electron mobility transistor (HEMT) structures based on the AlGaN/GaN heterostructure are extensively used in various applications such as gas sensors [1,2], THz detectors [3,4,5,6] and emitters [7,8], and high-power microwave devices [9,10,11,12]. The lattice-matched (LM) InAlN/GaN heterostructures are very attractive for the development of HEMTs as they possess no degradation due to mechanical stress and exhibit high chemical and thermal stability, demonstrated at up to 1000 ◦C [16,17]. The use of thinner LM-InAlN barrier allows for the achievement of much higher two-dimensional electron gas (2DEG) densities than that in standard AlGaN/GaN HEMT structures with the same barrier thickness [18]. The quaternary LM-InAlGaN barrier layer with indium content of 16.5 ± 0.2% and thickness of only 9 nm was developed for GaN-based heterostructures on sapphire substrate and investigated studying material structural properties, optical and electrical characteristics of the test devices

Samples

Results

Band Diagram of the Heterostructure

Schottky Contact to 2DEG

Photoluminescence of the Heterostructure

Conclusions