Atmospheric pressure metalorganic vapor phase epitaxial growth and characterization of high quality GaN on sapphire (0001) substrates are reported. Using AlN buffer layers, GaN thin films with optically flat surfaces free from cracks are successfully grown. The narrowest x-ray rocking curve from the (0006) plane is 2.70' and from the (2024) plane is 1.86'. Photoluminescence spectra show strong near band edge emission. The growth condition dependence of crystalline quality is also studied.

We evaluate the stacking faults (SFs) expansion from basal plane dislocations (BPDs) converted into threading edge dislocations (TEDs) under the current stress to the pn devices and analyzed the nucleation site of the SF by combined polishing, chemical etching in molten KOH, photoluminescence imaging, Focus ion beam, transmission electron microscopy, and Time-of-Flight secondary ion mass spectrometer techniques. It was found that the formation of SFs occurs upon the current stress levels of 400 A/cm2 where the diode area is not including BPDs in the drift layer after the high current stress, and the high current stress increases the SFs expansion density. It was also found the dependence of the junction temperature. The estimated activation energy for the expansion of SFs is Ea = 0.46 eV. The SF extends from the conversion point of the BPD into the TED within buffer layer. Even though BPDs converted into TEDs within the high doped buffer layer, SFs expand under high current stress.

Silicon dioxide thin films have been prepared at low temperatures from SiH4 and O2 by direct photo-induced CVD using a deuterium lamp. The growth rate is 75 Å/min at 84°C while no growth occurs below 180°C without deuterium lamp irradiation. UV and VUV light irradiation and an increase of the substrate temperature have effects of increasing the refractive index, and decreasing H incorporation and the amount of the oxide charge. The photo-CVD films deposited above 180°C show refractive indices of 1.45–1.46. Annealing in an O2 environment decreases the infrared absorptions due to Si–H stretching, Si–OH deformation and Si2O3 bondings as well as the oxide charge. The activation energies of the Si–H, the Si–OH deformation, the Si2O3 and the oxide charge obtained from the annealing characteristics are 0.18–0.19, 0.12, 0.19 and 0.12–0.13 eV, respectively. The reduction of Si–OH deformation absorption is considered to be closely related to the reduction of oxide charge.

The relationship between stacking faults and the position of the leakage current inside a triangular defect was analyzed. Triangular defects are categorized into two types on the basis of the current–voltage (I–V) characteristics. It was found that stacking faults (SFs) of the 3C structure inside a triangular defect increase leakage current at a reverse bias voltage as well as forward current at a low bias voltage, while SFs of the SF(4,2) structure inside a triangular defect do not lead to deterioration of device performance in this case.

We evaluate the velocity of stacking faults (SFs) expansion under various current and temperature levels on the pn diodes by electroluminescence (EL) observation in situ. The driving force of the SFs expansion is analyzed on the basis of the experimental results. The velocity of the SFs expansion increases in proportional to the current density at the every junction temperature levels. The activation energy for the velocity of the SFs expansion is estimated.