High-Quality AlN Film Grown on Sputtered AlN/Sapphire via Growth-Mode Modification

Abstract

Heteroepitaxy of high-quality AlN film is the key to advance the prosperity of deep-ultraviolet (DUV) devices when a large-size and low-cost native substrate is unavailable. Here, we proposed a strategy to obtain high-quality AlN film by combining growth-mode modification with sputtered AlN buffer using metal− organic chemical vapor deposition (MOCVD). Compared with the MOCVD AlN buffer, the sputtered AlN buffer consists of smaller and more uniform grains with better c-axis orientation, leading to a better growth-mode modification in the subsequent growth process. On one hand, the better c-axis orientation is inherited by the upper AlN epilayer, resulting in a lower screw dislocation density. On the other hand, the better growth-mode modification significantly suppresses edge dislocations by producing high-density nanoscale voids and many 90°bent dislocations. Therefore, the total threading dislocation density of the AlN film grown on the sputtered AlN buffer is dramatically reduced to an extremely low value of 4.7 × 10 7 cm −2 , which is 81.2% less than that of the AlN film grown on the MOCVD AlN buffer. This very simple yet effective technique demonstrates great potential for the massfabrication of low-cost and high-performance DUV devices.

Low-Temperature Epitaxial Growth of AlN Thin Films on a Mo Electrode/Sapphire Substrate Using Reactive Sputtering

“…That is to say, the in-plane orientational relationship between the AlN thin film and sapphire substrate was defined as AlN [1120]//sapphire [1010]. These results agree with other studies suggesting that epitaxial growth of AlN thin films can be achieved on sapphire substrates with an in-plane rotation of 30 • [26][27][28][29]. This rotation is caused by the lattice mismatch between the AlN and the sapphire substrate.…”

Deep-ultraviolet integrated photonic and optoelectronic devices: A prospect of the hybridization of group III–nitrides, III–oxides, and two-dimensional materials

“…In addition to their lower production costs and reduced substrate curvature, Susilo et al showed that sputtered thin HTA AlN (≤750 nm) template exhibited lower TDDs (7.2 × 10 8 cm -2 ) as compared to epi-taxially laterally overgrown (ELO) AlN/sapphire using MOVPE (1.1 × 10 9 cm -2 ). Their DUV LED devices (fabricated on the sputtered AlN templates) demonstrated DUV emission at around 268 nm, with output powers in the range of 0.65-0.72 mW at 20 mA, which is comparable to DUV LEDs fabricated on MOVPE-grown AlN templates [600] . Several MOVPE complex growth approaches were attempted, including lateral overgrowth of nitrogen-polar AlN domains with aluminum-polar AlN [612] and high-V/III-ratio-induced roughening [613] .…”

“…They also experimentally proved that the enhanced IQE performance was caused μ by the reduction in nonradiative recombination channels at the MQWs and the compositional modulations in the MQWs by virtue of the macrosteps of the AlN template [598,599] . As an alternative to MOVPE grown AlN templates, Susilo et al and Miyake et al investigated sputtered AlN templates with high temperature annealing (HTA) [600,434] . Sputtered AlN provide an avenue to achieve cost-efficient AlN templates with low TDDs [432,[601][602][603][604][605][606][607][608][609][610][611] .…”

Sec‐Eliminating the SARS‐CoV‐2 by AlGaN Based High Power Deep Ultraviolet Light Source

“…[ 36 ] On the other hand, the step‐bunching redirects the pre‐existing dislocation lines during the growth, and thus improving the crystal quality and device performance. [ 37,38 ] In this experiment, we modified the growth temperature and V/III ratio to control the surface morphology. And the step‐bunching density is modulated to get a trade‐off and the root mean square (RMS) roughness in a scanned area of 2 × 2 µm 2 is as low as 0.09 nm (as shown in Figure 1b).…”