Search

Record-low p-type resistivities of 9.7 and 37 Ω cm were achieved in Al0.7Ga0.3N and Al0.8Ga0.2N films, respectively, grown on single-crystal AlN substrate by metalorganic chemical vapor deposition. A two-band conduction model was introduced to explain the anomalous thermal behavior of resistivity and the Hall coefficient. Relatively heavy Mg doping (5 × 1019 cm−3), in conjunction with compensation control, enabled the formation of an impurity band exhibiting a shallow activation energy of ∼30 meV for a wide temperature range. Valence band conduction associated with a large Mg ionization energy was dominant above 500 K. The apparently anomalous results deviating from the classical semiconductor physics were attributed to fundamentally different Hall scattering factors for impurity and valence band conduction. This work demonstrates the utility of impurity band conduction to achieve technologically relevant p-type conductivity in Al-rich AlGaN. [ABSTRACT FROM AUTHOR]

The authors present optical and electrical data for long wavelength (573–601 nm) InGaN/GaN multiple quantum well light emitting diodes (LEDs) grown by metal organic chemical vapor deposition. These results are achieved by optimizing the active layer growth temperature and the quantum well width. Also, the p-GaN is grown at low temperature to avoid the disintegration of the InGaN quantum wells with high InN content. A redshift is observed for both the green and yellow LEDs upon decreasing the injection current at low current regime. In the case of the yellow LED, this shift is enough to push emission into the amber (601 nm). [ABSTRACT FROM AUTHOR]