The photoluminescence (PL) of the GaAs substrate excited by the electroluminescence of the active layer is adopted to determine the junction temperature in AlGaInP∕GaAs light emitting diodes. Based on the Varshni equation for GaAs, the temperature measured by this approach is consistent with that obtained by the emission peak energy shift approach. As the PL signal is generated within the substrate, no calibration dependent on the device structure is necessary to determine the junction temperature of the device.

An AlGaInP light-emitting diode (LED) with a Au/AuBe/SiO2/Si mirror substrate has been fabricated using wafer bonding. The bonded mirror-substrate LED is capable of emitting luminous intensity of 90 and 205 mcd under 20 and 50 mA injection, respectively. The emission wavelength was found to be independent of the injection current. This feature is attributed to the Si substrate providing a good heat sink.

This letter reports an approach for growing semipolar (11–22) GaN films with significantly reduced defect densities on m-plane sapphire substrates by incorporating a sequence of two in situ SiNx layers. The first SiNx layer is deposited on an initial epitaxial GaN layer and acts as a nanomask for preventing the propagation of extended defects. The second SiNx layer is deposited just after subsequent epitaxial GaN overgrowth begins to form self-organized GaN islands, which encourages further GaN growth to initiate from the exposed island sidewalls while blocking the penetration of the remaining defects. X-ray rocking curve measurements show that our semipolar GaN films provide relatively low full width at half maximum values at 0.119° along both the [11–23] and [10–10] directions. Additionally, transmission electron microscopy analyses confirm that our semipolar GaN films provide a significantly reduced density of threading dislocations down to ∼6 × 108 cm−2, which is two orders of magnitude less than those of conventionally deposited films.

No abstract