Erbium-doped GaN (GaN:Er) epilayers were synthesized by metal organic chemical vapor deposition. GaN:Er waveguides were fabricated based on four different GaN:Er layer structures: GaN:Er/GaN/Al2O3, GaN:Er/GaN/AlN/Al2O3, GaN:Er/GaN/Al(0.75)Ga(0.25)N/AlN/Al2O3, and GaN/GaN:Er/GaN/Al2O3. Optical loss at 1.54 μm in these waveguide structures has been measured. It was found that the optical attenuat...

Replacing SiC substrates with the highest thermal conductivity material available, diamond (κ up to 2000 W/mK), will result in significantly lower thermal resistance AlGaN/GaN HEMTs. In this work we combine Raman thermography and thermal simulation to assess the thermal resistance of state-of-the-art GaN-ondiamond HEMTs. INTRODUCTION The RF output power density achievable for GaN-based high ele...

Softmax GAN is a novel variant of Generative Adversarial Network (GAN). The key idea of Softmax GAN is to replace the classification loss in the original GAN with a softmax cross-entropy loss in the sample space of one single batch. In the adversarial learning of N real training samples and M generated samples, the target of discriminator training is to distribute all the probability mass to th...

In this project we try to explore the possibility of using Conditional Adversarial Networks (Conditional GAN) to enhance images. Conditional Adversarial Networks can learn the image-to-image translation and adapt the translation to future images. We try to use Conditional GAN to learn the translation between images from original images and enhanced images and automatically translate original im...

The p-type AlGaN electron blocking layer (EBL) is widely used in InGaN/GaN light-emitting diodes (LEDs) for electron overflow suppression. However, a typical EBL also reduces the hole injection efficiency, because holes have to climb over the energy barrier generated at the p-AlGaN/p-GaN interface before entering the quantum wells. In this work, to address this problem, we report the enhancemen...

Lattice constants of single phase gallium nitride were measured from room temperature to 1273 IS using high temperature x-ray powder diffraction. The data were used to calculate the epitaxial misfits using the epitaxial relationships, GaN(OOOl)]]A.1203(OO01) and GaN[10i0]]]A120s[1 1201 and GaN(OOOl#iH-SiC(OOO1) and GaN[lOiO]]]6H-SiC[lOiO], reported in the literature. Using the above relationshi...

In this work, the physical based device model of AlGaN/GaN high electron mobility transistors (HEMTs) has been established and the corresponding device operation behavior has been investigated also by using Sentaurus TCAD from Synopsys. Advanced AlGaN/GaN hetero-structures with GaN cap layer and AlN spacer have been considered and the GaN cap layer and AlN spacer are found taking important role...

Elasto-plastic mechanical deformation behaviors of c-plane (0001) and nonpolar GaN single crystals are studied using nanoindentation, cathodoluminescence, and transmission electron microscopy. Nanoindentation tests show that c-plane GaN is less susceptible to plastic deformation and has higher hardness and Young's modulus than the nonpolar GaN. Cathodoluminescence and transmission electron micr...

High-power operation of AlGaN/GaN highelectron-mobility transistors (HEMTs) requires efficient heat removal through the substrate. GaN composite substrates including high-thermal-conductivity substrates such as SiC and diamond are promising, but these composite substrates require careful attention to thermal resistances at GaN-substrate interfaces. We report on thermal characterization of GaN-o...