Degenerate Layer at GaN/Sapphire Interface: Influence on Hall-Effect Measurements

Determination of two-dimensional electron and hole gas carriers in AlGaN/GaN/AlN heterostructures grown by Metal Organic Chemical Vapor Deposition

Resistivity and Hall effect measurements on nominally undoped Al0.25Ga0.75N/GaN/AlN heterostructures grown on sapphire substrates prepared by metal organic chemical vapor deposition have been carried out as a function of temperature (20–300 K) and magnetic field (0–1.4 T). Variable magnetic field Hall data have been analyzed using the improved quantitative mobility spectrum analysis technique. ...

Formation mechanism of a degenerate thin layer at the interface of a GaN/sapphire system

Optical characterization of AlNÕGaN heterostructures

AlN/GaN/sapphire heterostructures with AlN gate film thickness of 3–35 nm are characterized using photoreflectivity ~PR! and photoluminescence ~PL! spectroscopy. Under a critical AlN film thickness, the luminescence from the GaN channel layer near the interface proves to be excitonic. No luminescence related to the recombination of the two-dimensional electron gas ~2DEG! is observed, in spite o...

Liquid-immersion laser micromachining of GaN grown on sapphire

Liquid-immersion nanosecond-pulsed laser micromachining is introduced as an efficient way for device isolation and rapid prototyping on GaN-on-sapphire wafer. Using deionized water as an ambient medium for laser micromachining, smooth trenches that are free from redeposition can be formed in the GaN layer. Coupled with the large difference between the ablation thresholds and ultraviolet absorpt...

Epitaxial strain energy measurements of GaN on sapphire by Raman spectroscopy

This study reports a non-destructive method of measuring the residual strain in the GaN epilayer grown on sapphire substrate by micro-Raman spectroscopy. Operating in confocal mode this method allows a depth-dependent measurement of residual strain in the epitaxial layer without prior treatment of the sample. This approach to measurement of residual strain is demonstrated on GaN epitaxial films...