Diode structures based on p-GaN for optoelectronic applications in the near-ultraviolet range of the spectrum

It was previously reported that spectrally matched n-SiC and n-GaN-based MI S Schottky barrier diode structures exhibited optical emission and photosen sitivity in the near-ultraviolet (UV) range of the spectrum and rectificati on at elevated temperatures. However, such structures were not practical du e to the low mechanical and thermal stability of the semitransparent Au con tacts. In addition, we experienced difficulties in achieving stable optical emission from the n-GaN-based structures. In this work various Schottky ba rrier diode structures based on p-type GaN layers grown on sapphire with si licon (Si), boron nitride (BN), and silicon dioxide (SiO2) interfacial laye rs were investigated. Blue and wide-spectrum optical emissions at forward a nd reverse bias, respectively, and photosensitivity were observed from thes e structures. A spectral match in the range of 365-400 nm between the light emitting diode (LED) and photodetector structures fabricated on the same s ubstrate was achieved. A total Lambertian radiant UV power of similar to 46 6 muW was measured from a blue/UV LED at 22 V. UV-transparent and electrica lly conductive SnOx layers were fabricated, characterized, and employed for fabrication of p-GaN-based photodiode structures. (C) 2000 American Vacuum Society. [S0734-211X(00)17906-5].