First‐principles electronic structure calculations on wurtzite AlN, GaN, and InN reveal crystal‐field splitting parameters ΔCF of −217, 42, and 41 meV, respectively, and spin–orbit splitting parameters Δ0 of 19, 13, and 1 meV, respectively. In the zinc blende structure ΔCF≡0 and Δ0 are 19, 15, and 6 meV, respectively. The unstrained AlN/GaN, GaN/InN, and AlN/InN valence band offsets for the wurtzite (zinc blende) materials are 0.81 (0.84), 0.48 (0.26), and 1.25 (1.04) eV, respectively. The trends in these spectroscopic quantities are discussed and recent experimental findings are analyzed in light of these predictions.

Valence band splittings and band offsets of AlN, GaN and InN.

Emerging trends in wide band gap semiconductors (SiC and GaN) technology for power devices

We report the fabrication of ultraviolet photodetector on non-polar (11–20), nearly stress free, Gallium Nitride (GaN) film epitaxially grown on r-plane (1–102) sapphire substrate. High crystalline film leads to the formation of two faceted triangular islands like structures on the surface. The fabricated GaN ultraviolet photodetector exhibited a high responsivity of 340 mA/W at 5 V bias at room temperature which is the best performance reported for a-GaN/r-sapphire films. A detectivity of 1.24 × 109 Jones and noise equivalent power of 2.4 × 10−11 WHz−1/2 were also attained. The rise time and decay time of 280 ms and 450 ms have been calculated, respectively, which were the fastest response times reported for non-polar GaN ultraviolet photodetector. Such high performance devices substantiate that non-polar GaN can serve as an excellent photoconductive material for ultraviolet photodetector based applications.

Fabrication of non-polar GaN based highly responsive and fast UV photodetector

Review of technology for normally-off HEMTs with p-GaN gate

Metal oxide based non-enzymatic electrochemical sensors for glucose detection

Distinct light emission peaks from monolayers of GaSb quantum wells in GaAs were observed. Discrete atomic layers of GaSb for the wetting layer prior to quantum dot formation give rise to transition peaks corresponding to quantum wells with 1, 2, and 3 ML. From the transition energies the authors were able to deduce the band offset parameter between GaSb and GaAs. By fitting the experimental data with the theoretical calculated result using an 8×8 k∙p Burt’s Hamiltonian along with the Bir-Picus deformation potentials, the strain-free (fully strained) valence band discontinuity for this type-II heterojunction was determined to be 0.45eV (0.66eV).

https://ir.nctu.edu.tw:443/bitstream/11536/10691/1/000247305400085.pdf

Discrete monolayer light emission from GaSb wetting layer in GaAs

http://ir.lib.ksu.edu.tw/bitstream/987654321/17375/2/Investigation%20of%20etch%20characteristics%20of%20non-polar%20GaN%20by%20wet%20chemical%20etching.pdf

Investigation of etch characteristics of non-polar GaN by wet chemical etching

A step-stage InGaN/GaN multiquantum-well (MQW) structure can enhance the efficiency of GaN-based light-emitting diodes (LEDs). Compared to dual-stage MQW LEDs, the step-stage MQW LEDs have lower forward voltage and higher light output. The measured light output power of step-stage LEDs operating at 350 mA shows an increase of approximately 23% with an external quantum efficiency (EQE) increase of 6.6%, when compared to dual-stage LEDs.

Enhanced Performance of Nitride-Based Blue LED With Step-Stage MQW Structure

In this study, we had demonstrated the direct growth of nonpolar a-plane GaN on an r-plane sapphire by metal organic chemical vapor deposition (MOCVD) without any buffer layer. First, in this experiment, we had determined the optimum temperature for two-step growth, including obtaining three-dimensional (3D) GaN islands in the nucleation layer and coalescing with a further two-dimensional (2D) growth mode. The result shows that the nucleation layer grown under high temperature (1150 °C) leads to large islands with few grain boundaries. Under the same temperature, the effect of the V/III ratio on the growth of the overlaying GaN layer to obtain a flat and void free a-plane GaN layer is also studied. The result indicates one can directly grow a smooth epitaxial layer on an r-plane sapphire by changing the V/III ratio. The rms roughness decreases from 13.61 to 2.02 nm. The GaN crystal quality is verified using a mixed acid to etch the film surface. The etch pit density (EPD) is 3.16 ×107 cm-2.

https://iopscience.iop.org/article/10.1143/JJAP.49.04DH05/pdf

Shyh-Jer Huang

Papers

Discrete monolayer light emission from GaSb wetting layer in GaAs

Investigation of etch characteristics of non-polar GaN by wet chemical etching

Enhanced Performance of Nitride-Based Blue LED With Step-Stage MQW Structure

Direct Growth of a-Plane GaN on r-Plane Sapphire by Metal Organic Chemical Vapor Deposition

The improvement of GaN-based LED grown on concave nano-pattern sapphire substrate with SiO2 blocking layer