Berlin 2012 – scientific programme

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HL: Fachverband Halbleiterphysik

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

HL 83.3: Topical Talk

Thursday, March 29, 2012, 16:00–16:30, EW 201

Advantages and issues of m-plane freestanding GaN substrates grown by halide vapor phase epitaxy for InGaN and AlGaN epitaxial growth — •Shigefusa Chichibu¹, Kouji Hazu¹, Pierre Corfdir², Jean-Daniel Ganière², Benoît Deveaud-Plédran², Nicolas Grandjean², Shuich Kubo³, Hideo Namita³, Satoru Nagao³, Kejji Fujito³, and Kenji Shimoyama³ — ¹Tohoku Univ., Sendai, Japan — ²EPFL, Lausanne,Switzerland — ³Mitsubishi Chemical Corp., Ushiku, Japan

We will discuss the subject given in the title. As long as coherent growth is maintained, the degree of tilt and twist mosaics of the epilayers is similar to the substrate. However, the formation of basal-plane stacking faults (BSFs) is hard to avoid in the case of lattice-mismatched thick films. For the pseudomorphic In_xGa_1−xN (x≤0.14) films, improved quantum efficiency and short radiative lifetime are achieved for the near-band-edge emission. As the surface flatness is improved, however, the In-incorporation efficiency becomes lower than the cases for c-plane growth and m-plane growths on defective GaN bases. Atomically smooth and coherent m-plane AlGaN/GaN heterostructures exhibit a luminescence signal originating from the recombination of 2DEG and photoexcited holes. Slight but nonzero, grown-in anisotropic tilt mosaics of the substrates give rise to the formation of surface striations and inclined planes, and also planar-defect networks in the epilayers. The origins of characteristic CL intensity patterns will be discussed, using the spatio-time-resolved CL and conventional time-resolved PL measurements.