Gallium Nitride (GaN) has potential application in optoelectronic and electronic devices, which are capable of operating at high temperature, high power and in harsh environments (Nakamura et al 1997, Morkoc et al 1994). In addition, GaN powders themselves could be used as high quality phosphors. GaN has low electron affinity value of 2.7-3.3 eV compared to carbon nanotubes (CNTs), zinc oxide (...

In organometallic vapor phase epitaxial growth of group III nitrides on sapphire, insertion of a low temperature interlayer is found to improve crystalline quality of AlxGa1-xN layer with x from 0 to 1. Here the effects of the low temperature deposited GaN or AlN interlayers on the structural quality of group III nitrides is discussed. INTRODUCTION From the late 60’s to the early 70’s Maruska a...

We report the development of 520–540 nm green light emitting diodes LEDs grown along the nonpolar a axis of GaN. GaInN /GaN-based quantum well structures were grown in homoepitaxy on both, a-plane bulk GaN and a-plane GaN on r-plane sapphire. LEDs on GaN show higher, virtually dislocation-free crystalline quality and three times higher light output power when compared to those on r-plane sapphi...

The effect of air/AlGaN and GaN/substrate polarization charges on the performances of GaN-based HEMTs have been investigated. We find that surface charges and, with a minor extend, GaN/substrate charges are responsible for the observed premature saturation of the dc output characteristics. Moreover, our work show that the polarization charges and holes trap appear as the source of the drain cur...

M-plane GaN(1 1 00) is grown by plasma assisted molecular beam epitaxy on ZnO(1 1 00) substrates. A low-temperature GaN buffer layer is found to be necessary to obtain good structural quality of the films. Well oriented (1 1 00) GaN films are obtained, with a slate like surface morphology. On the GaN(1 1 00) surfaces, reconstructions with symmetry of c(2x2) and approximate "4×5" are found under...

We study the concept of double-heterostructure quantum well (DHQW) InAlN/GaN/AlGaN high electron mobility transistor (HEMT) for higher device robustness and less degradation. Physics-based device simulation proves that the back barrier blocks the carrier injection into the device buffer. However, the energy of the injected electrons in the buffer is higher for any quantum well design in InAlN/G...

The LDRD entitled “Role of Defects in 111-Nitrde Based Devices” is aimed to place Sandia National Laboratory at the forefront of the field of GaN materials and devices by establishing a scientific foundation in areas such as material growth, defect characterization/modeling, and processing (metalization and etching) chemistry. In this SAND report we summarize our studies such as i) the MOCVD gr...

We report the effect of chemical etching of p-GaN using molten KOH:NaOH solution on leakage currents, light output power, and electrostatic discharge ESD characteristics of GaN light-emitting diodes LEDs . Photoluminescence and capacitance–voltage measurement indicated that a deep donor–acceptor pair DDAP was densely concentrated near the p-GaN surface region 18 nm and the defects were effectiv...

Light-emitting diodes (LEDs) become an attractive alternative to conventional light sources due to high efficiency and long lifetime. However, different material properties between GaN and sapphire cause several problems such as high defect density in GaN, serious wafer bowing, particularly in large-area wafers, and poor light extraction of GaN-based LEDs. Here, we suggest a new growth strategy...

The growth of GaN films on silicon or sapphire substrates has not been straightforward due to their large mismatch ('13%). SiC is structurally the closest material to GaN (especially cubic form) and has a small lattice mismatch (3.5%) between SiC and GaN, and therefore can be useful as the substrate for GaN. Single-crystal wafers of cubic SiC and GaN, however, are hard to obtain and have not be...