Effect of Substrate Surface on Deposition of AlGaN: A Molecular Dynamics Simulation

Abstract

The growth of AlGaN has been extensively studied, but corresponding research related to the effect of AlN substrate surface has rarely been reported in literature. In this article, the effects of AlN substrate surface on deposition of AlGaN films were investigated by molecular dynamics (MD) simulations. (0001) Al-terminated and 0001 N-terminated AlN were considered as substrates. The quality of surface morphology and atomic scale structure of deposited AlGaN film are discussed in detail. The results show that the surface morphology and crystal quality of AlGaN film grown on (0001) Al-terminated AlN surface are better than for that grown on 0001 N-terminated AlN surface under various growing temperatures and Al/Ga injection ratios between Al and Ga. This can be attributed to the higher mobility of Al and Ga adatoms on the (0001) Al-terminated AlN surface. These findings can provide guidance for the preparation of high-quality AlGaN thin films on AlN substrate.

Applications and Impacts of Nanoscale Thermal Transport in Electronics Packaging

“…Moreover, phonon thermal conductivity-mean free path spectra of UWBG materials obtained through experimental and theoretical approaches can be used the predict size dependence of thermal conductivity [181,210]. Finally, the h BD s between b-Ga 2 O 3 / diamond [132], i-Ga 2 O 3 /metal [133], and AlN/AlGaN [211] interfaces have been obtained using a variety of experimental and theoretical approaches. These findings generally show that the already low thermal conductivity of UWBG materials is further reduced in their thin film form; when combined with the low h BD between these materials and their substrates, a thermal bottleneck can form and result in inadequate heat dissipation.…”

Review—Review of Research on AlGaN MOCVD Growth

“…Similar study results were obtained by Lundin et al and Touzi et al 53,43 Furthermore, Lundin et al also found that although the Al component decreased with the rise of III-nitride, the rate of decrease in the high ammonia atmosphere was significantly faster than that in the low. In addition, as the ratio of the III-nitride flow rate rose in the total gas, the growth rate also grews, 26,47,49,55,56 thus it was difficult to achieve rapid growth of the AlGaN layer and obtain a high Al component simultaneously by adjusting the III-nitride flow rate.…”

“…Research on the surface reaction.-In the layer grown by MOCVD, gas phase reactions and fluid transport determined the species, concentration and transport rate of the particles that reached the surface of the substrate, but the quality of layer growth, including surface morphology, impurity component and defect distribution depended to a large extent on the interaction between the gas phase precursor and the surface of the substrate, namely the surface reaction, which included adsorption, desorption, surface diffusion, adsorption of particles into the crystal lattice. 56 When the temperature was high or the long speed was slow, the particles reaching the surface could quickly diffuse from the adsorption site to the growth kinetics or corner, and then merged into the crystal lattice, namely two-dimensional kinetics flow growth. When the temperature was low, the growing velocity was faster or the chemical bond between the adsorbed particles and the adsorption site was stronger, the particles reaching the surface could not rapidly diffuse from the adsorption site to the step or the corner, so that three-dimensional volmer-weber occurred, causing a large number of dislocations and uneven distribution of grain boundary and impurities.…”

Strain-Induced Spectral Red-Shifting from Nanoscale Frustum Arrays Fabricated over InGaN/GaN Quantum Wells for Light-Emitting Applications

“…A 2D molecular dynamics study is undertaken to compare the effects of strain induction between such inverted nanoconical frustum with typical nontapered nanopillars of base diameters ranging from 10 to 100 nm, set up using c -plane wurtzite GaN blocks. The simulations are carried out using the software package LAMMPS with a Stillinger–Weber potential for InAlGaN − on a structure corresponding to the wafer used in the experiments. The GaN blocks are fixed at the bottom ( y = 0) with a compressive strain of 0.023% to emulate a boundary that is lattice-matched to a partially relaxed GaN buffer with a biaxial stress of 1 GPa.…”