Studies on GaN nanostructures grown by molecular beam epitaxy and TiO2 thin films grown by atomic layer deposition

Abstract

(Al/Ga/In)-N compounds namely AlN, GaN and InN with respective bandgaps of 6.2, 3.4 and 0.6 eV constitute the group III nitride family. These wide-range bandgap materials possess several remarkable properties that make them particularly attractive for reliable solid state optoelectronic device applications. They have low dielectric constants with high thermal conductivity pathways, exhibit high bond strengths and high melting temperatures1-3. The large bond strengths inhibit dislocation motion and improve reliability in comparison to other II-VI and III-V materials1. In addition, group III-nitrides are resistant to chemical etching and hence should allow GaN-based devices to be reliably operated in harsh environments4, 5. With large avalanche breakdown fields, high thermal conductivities, and large high-field electron drift velocities2, 4, 7-9, various high temperature and high-power microelectronic and optoelectronic devices such as passivation barriers, ohmic contacts in integrated circuits, blue light-emitting diodes, candela-class blue-light emitting diodes, green and yellow light-emitting diodes, UV photodetectors, reflector stacks, high electron mobility transistors, hetero-structure field effect transistor, metal semiconductor field-effect transistors, and surface acoustic wave devices have been fabricated. Stimulated emission has been reported from optically pumped GaN and AlGaInN alloy double hetero-structure films2-4.