Berlin 2012 – scientific programme

Parts | Days | Selection | Search | Updates | Downloads | Help

HL: Fachverband Halbleiterphysik

HL 83: Focus Session: III-Nitride Heterostructures for Optoelectronics - Polarization Reduction, Green Gap and High In-containing Alloys

HL 83.5: Topical Talk

Thursday, March 29, 2012, 17:15–17:45, EW 201

Nonpolar and semipolar GaN on GaN, Si, and Sapphire substrates — Vitaliy Avrutin, Natalia Izioumskaia, Ümit Özgür, and •Hadis Hadis Morkoç — Virginia Commonwealth University, Richmond, VA 23284-3072

Polar nature of GaN necessitates investigating non-polar and semi-polar orientations to circumvent adverse effects. In this presentation, mainly the growth and optical properties of non-polar, namely (11bar00) orientation, and semi-polar, namely (11bar01) and (112bar2) orientations, of GaN and InGaN/GaN heterostuctures will be discussed. (11bar00) and (11bar01)-oriented GaN layers were grown on patterned Si substrates, while (112bar2) GaN films on m-sapphire by metal organic chemical vapor deposition (MOCVD). For (11bar01)GaN films grown at high reactor pressure (200 Torr), steady-state and time-resolved PL measurements have revealed bright luminosity and very long carrier decay times (1.8 ns), which are comparable to those for the state-of-the-art c-plane GaN templates prepared by in situ epitaxial lateral overgrowth using silicon nitride nano-network. Low reactor pressure of 30 Torr required for the growth of m-plane GaN on Si(112) leads to weaker luminescence and rapid carrier decay likely due to carbon contaminations, which both could be improved significantly by subsequent overgrowth at higher pressures. The long radiative lifetimes for the (11bar01)GaN layers show that the semipolar material has a great promise for light emitting and detecting devices.