The butt-coupled (BT) sampled grating distributed Bragg reflector laser diode (SGDBR-LD) was designed and fabricated using planar buried heterostructure (PBH), enabling a low threshold current and a stable fundamental transverse mode. The but-coupled SGDBR-LD's with target tuning ranges of 44.4nm was fabricated, and the tuning ranges were experimentally measured to be 44.4nm. The measured peak periods of the fabricated SGDBR-LD's were well matched with theoretical values and output power is close to calculated values. The side mode suppression ratio of more than 35dB was obtained in the whole tuning range. The output power variation was less than 5dB, which is 4dB smaller than that of RWG structure.
A method for fabrication of nano-scale GaN structure by inductively coupled plasma etching is proposed, exploiting a thermal dewetting of Pt thin film as an etch-mask. The nano-scale Pt metal islands were formed by dewetting of continuous film on SiO<sub>2</sub> dielectric materials during the rapid thermal annealing process. For the Pt films with thickness of 30 nm, temperatures of > 600°C initiate pattern formation and the dewetting of Pt films. Controlling the annealing temperature and time as well as the thickness of Pt metal film could manifest the size and density of Pt islands. The activation energy for initiation of Pt metal dewet was calculated to be 23.2 kJ/mole. The islands show good resistance against dry etching using CF<sub>4</sub> based plasma for dielectric etching, indicating that the metal island by dewetting of thin film is suitable for etch mask in the fabrication of nano-scale structures. This fabrication method was also proven to be effective in the fabrications of GaN nanocolumns with widths as small as nanometer scale.