Blue laser diodes (LDs) were fabricated on m-plane oriented GaN substrates by atmospheric-pressure metalorganic chemical vapor deposition. Typical threshold current for stimulated emission at a wavelength λ of 463 nm was 69 mA. Blueshift of the spontaneous emission peak with increasing injection current was examined in LDs fabricated on m- and c-plane GaN substrates. Blueshifts for the m-plane LD (λ=463 nm) and the c-plane LD (λ=454 nm) with an injection current density just below threshold were about 10 and 26 nm, respectively. These results confirm that the blueshift in quantum-wells fabricated on m-plane oriented substrates is smaller than on c-plane oriented substrates due to the absence of polarization-induced electric fields.

The effects of slight misorientation from c-plane (0001) sapphire (α-Al2O3) substrates on GaN surface morphologies and electroluminescence (EL) properties were studied. The GaN layers were grown using a two-step growth method under atmospheric pressure by metalorganic chemical vapor deposition (MOCVD). When using around 0.17° misoriented sapphire substrate tilted toward both <1120> and <1100> directions, a small step-type morphology appeared. On the other hand, using c-plain substrate or substrates with the misorientation angle larger than approximately 0.25° from the c-plane, a scale-shaped morphology appears. We also found that the misorientation of the substrate significantly affects the uniformity of the EL image. On the other hand, the light output powers of the light-emitting diodes (LEDs) fabricated on the substrates with different misorientations were almost the same in spite of the different surface morphologies.

GaN-based GaN1−xAsx alloys, x⩽0.043, were grown by metalorganic chemical vapor deposition. The results of high-resolution x-ray diffraction measurements indicated that no phase separation was observed over a range of up to x=0.043 and both the lattice constants c and a increased with an increase in arsenic composition. In cathodoluminescence measurements, the GaN1−xAsx showed a large band gap bowing parameter of 22.1eV. Furthermore, we have experimentally revealed that the valence band offset for the GaN1−xAsx∕GaN is very large, and we have proposed the band gap energy diagram of GaN1−xAsx utilizing an arsenic deep donor level.

We report on a novel method using lattice matched AlInN as the current confinement layer for inner stripe laser diodes. Optimisation of the sample preparation techniques and metal organic chemical vapor deposition (MOCVD) regrowth conditions resulted in an inner stripe laser diode with threshold current density of $3:3 { 3:5 kA/cm 2 and slope efficiency of 1.6 W/A. The cw lifetime and other characteristics of the inner stripe laser diode are discussed. Simulation data have also shown that this structure is beneficial for reducing operating voltage when compared to a conventional ridge waveguide structure. #

Effectively atomically flat interfaces over a macroscopic area (200 μm o/) have been achieved in GaAs/AlAs quantum wells (QWs) with well widths of 4.8 to 12 nm grown on (411)A GaAs substrates by molecular-beam epitaxy (MBE). A single and very narrow photoluminescence peak (FWHM)=7.7 meV) was observed at 742.6 nm for the QW with a well width of 4.8 nm at 77 K. The linewidth is comparable to that of growth-interrupted QWs grown on (100)-oriented GaAs substrates by MBE. These results indicate that the surface of GaAs and AlAs grown on the (411)A GaAs substrates are extremely flat and stable on the (411)A plane.