Effects of laser sources on the reverse-bias leakages of laser lift-off GaN-based light-emitting diodes

The KrF pulsed excimer laser (248nm) and the frequency-tripled neodymium doped yttrium aluminum garnet laser (355nm) have been used to separate GaN thin films from sapphire substrates and transfer to bond other substrate. However, these processes would increase the dislocation density, resulting in an increase of the leakage current. In this study, the effects of these two laser sources on the reverse-bias leakages of InGaN-GaN light-emitting diodes were studied. (c) 2007 American Institute of Physics

Effects of annealing temperature on electrical resistance of bonded n-GaAs wafers

The electrical characteristics and microstructures of n-type (100) GaAs bonded interfaces were systematically investigated. Experimental results indicated that GaAs did not bond directly to itself, but via an amorphous oxide layer at 400 degreesC. When temperatures increased above 400 degreesC, the oxide bonded area declined and finally disappeared. Electrical resistance decreased with bonding temperature. However, the resistance increased with temperatures exceeding 850 degreesC. (C) 2004 American Institute of Physics

First-principles analysis of interfacial nanoscaled oxide layers of bonded N- and P-type GaAs wafers

First-principles analysis is applied in relating microstructures with properties of interfacial nanoscaled oxide layers of bonded N- and P-type GaAs wafers. Using high-resolution transmission electron microscope results, the detailed atomic arrangements of materials specimen can be obtained and fed into the first-principles calculations. Therefore, the corresponding electronic structure and associated property can be reliably derived to identify responsible microstructural features. The electrical performance is found to be closely related to the variation of nanosized interface morphology and types of wafers. (c) 2007 American Institute of Physics

Nanoscaled interfacial oxide layers of bonded n- and p-type GaAs wafers

This work examined in detail the electrical characteristics and microstructures of in- and antiphase bonded interfaces for both n- and p-type GaAs wafers treated at 500 and 600 degrees C, respectively. The n-GaAs wafers did not bond directly to itself but instead via an amorphous oxide layer at 500 degrees C. These temperatures are lower than most other works. The nonlinear behavior of the current versus the voltage is related to the potential barrier formed at the continuous oxide interface. Both experimental observation and first-principles calculations confirm the existence of this barrier. The higher interface energy for the antiphase bonding tends to stabilize the interfacial oxide layer. The evolution of interfacial layers occurred much faster for the p-type wafers than for n-type wafers. Electrical performance was found to be closely related to the variation of nanosized interface morphology. (c) 2006 American Institute of Physics

Anomalous electrical performance of nanoscaled interfacial oxides for bonded n-GaAs wafers

Electrical performance was found to be closely related to the variation of nanosized interface morphology in previous studies. This work investigated in detail the microstructural development of in- and anti-phase bonded interfaces for n-type (100) GaAs wafers treated at 500, 600, 700 and 850 degrees C. The interfacial energy of anti-phase bonding is higher than that of in-phase bonding based on the first-principles calculations. The higher interface energy tends to stabilize the interfacial oxide layer. The continuous interfacial oxide layer observed below 700 degrees C can deteriorate the electrical property due to its insulating property. However, the existence of nanoscaled oxide at anti-phase bonded interfaces can improve the electrical conductivity at 700 degrees C. This is due to the suppression of the evaporation of As atom by the interfacial nanoscaled oxides based on the analysis of autocorrelation function and energy dispersive x-ray spectroscopy. (c) 2006 American Institute of Physics