Effect of Graded Al_xGa_1-xN Layers on the Properties of GaN Grown on Patterned Si Substrates

Abstract

2.2-m-thick crack-free GaN films were grown on patterned Si substrates. The crack-free GaN films were obtained by patterning Si substrate and optimizing the graded Al x Ga 1Àx N layers. With the increase of the graded Al x Ga 1Àx N layer thickness, the GaN crystal quality improved as judged from the X-ray diffraction data. By applying multi-Al x Ga 1Àx N layers on the patterned Si substrate, a 31% reduction of tensile stress for the GaN film was obtained as measured by micro-Raman. For the AlGaN/GaN high electron mobility transistor grown on 1 Â 1 cm 2 larger patterns, the device exhibits maximum drain current density of 776 mA/mm and maximum transconductance of 101 mS/mm.

Measuring the depth profiles of strain/composition in AlGaN-graded layer by high-resolution x-ray diffraction

“…[5][6][7][8][9] Moreover, there have been further demonstrations that compositionally graded Al x Ga 1Àx N may also serve as strain transition buffer layers and dislocation filters for the growth of crack-free GaN on Si(111) substrates. [10][11][12] The depth profile of the aluminum content is the key factor in modifying the properties of graded Al x Ga 1Àx N layers. Thus, a crucial issue in the growth of these layers is the precise control of the Al flux so that the composition changes controllably with depth.…”

Near milliwatt power AlGaN-based ultraviolet light emitting diodes based on lateral epitaxial overgrowth of AlN on Si(111)

“…Extensive work has been dedicated to the development of the growth of GaN on Si(111) substrates as templates in GaN visible light emitting diodes. [1][2][3][4] However, for UV LED purposes, it is essential to develop AlN growth on Si (111) substrates to avoid generated UV light reabsorption for backemission configuration. The growth of crack-free and lowdislocation density AlN on Si(111) is more challenging than the growth of GaN on Si(111) because there is a larger lattice mismatch between AlN and Si(111) ($19%) that leads to higher density of dislocations and crack-initiating stress.…”

High-Performance Solar-Blind Ultraviolet Photodetectors Based on β-Ga2O3 Thin Films Grown on p-Si(111) Substrates with Improved Material Quality via an AlN Buffer Layer Introduced by Metal–Organic Chemical Vapor Deposition

“…In fact, there has always been much more interest in obtaining foreign semiconductor growth on Si substrates to realize optoelectronic integration . The successful and impressive story of III-nitrides heteroepitaxially grown on Si substrates is well known and has pushed forward the rapid progress of nitride-based light-emitting diodes and power electronics. − For the growth of β-Ga 2 O 3 (an oxide semiconductor) on Si substrates, however, two issues must be addressed: (1) the large lattice mismatch and (2) the negative effect of the native amorphous oxide layer on the Si surface, which is usually formed in the very initial stage of oxide thin-film growth, resulting in the degradation of structural quality.…”