  V-pit-defects in GaN-based light-emitting diodes induced by dislocations are
considered beneficial to electroluminescence because they relax the strain in
InGaN quantum wells and also enhance the hole lateral injection through
sidewall of V-pits. In this paper, regularly arranged V-pits are formed on
c-plane GaN grown by metal organic vapor phase epitaxy on conventional c-plane
cone-patterned sapphire substrates. The size of V-pits and area of flat GaN can
be adjusted by changing growth temperature. Five pairs of InGaN/GaN
multi-quantumwell and also a light-emitting diode structure are grown on this
V-pit-shaped GaN. Two peaks around 410 nm and 450 nm appearing in both
photoluminescence and cathodeluminescence spectra are from the semipolar
InGaN/GaN multi-quantum-well on sidewalls of V-pits and cplane InGaN/GaN
multi-quantum-well, respectively. In addition, dense bright spots can be
observed on the surface of light-emitting diode when it works under small
injection current, which are believed owing to the enhanced hole injection
around V-pits.
