Characterizations of Doping Effects in Nitride Films

• Main Author: 張富欽
• Other Authors: 陳衛國
• Format: Others
• Language: en_US
• Published: 2005
• Online Access: http://ndltd.ncl.edu.tw/handle/67030038710784166379

博士 === 國立交通大學 === 電子物理系所 === 93 === We have carried out systematic studies on epitaxial growth of d In isoelectronic doping p-GaN using metalorganic vapor phase epitaxy technique (MOVPE). For the isoelectronic In-doping effects on Mg-doped GaN films, The preliminary results indicate that when In atoms are added, the surface morphology is greatly improved, and a virtually featureless structure can be obtained. properties, The Hall resulting optimum hole concentration and resistivity are 9× 10e17 cm-3 and 1 Ω-cm, respectively. Perhaps the most striking result is the observance of a linear I-V characteristic on the as-deposited sample, which indicates the good Hall properties associated with such types of film. The Photoluminescence (PL) studies of In-doped GaN:Mg films revealed that the Mg-related emission at 3.1 eV is enhanced by more than one order of magnitude on the shoulder of the broad band centered at 2.8 eV for GaN:Mg after an optimal In concentration was added into the films. This enhancement of the 3.1 eV band is believed to be associated with the reduction in the number of self-compensation centers. A slow decay in PL intensity evolution was also observed, which may be ascribed to a local energy barrier that impedes carriers that relax into the valence band. The temperature dependences of the decay time constants were measured and a barrier energy as high as ~ 103±7 meV was obtained for In-doped GaN:Mg as compared with 69±8 meV for GaN:Mg.