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Scanning electron microscopy (SEM) cathodoluminescence (CL) experiments were used to determine the existence and direction of piezoelectric fields in a commercial InGaN multiple-quantum-well (MQW) light-emitting diode (LED). The CL emission peak showed a blueshift with increasing reverse bias due to the cancellation of the piezoelectric field. A full compensation of the piezoelectric field was observed followed by a redshift with a further increase of reverse bias, indicating that flat-band conditions had been reached. We determined the piezoelectric field points in the [000-1] direction and estimated the magnitude to be approximately 1 MV/cm. SEM-CL carrier generation density variation and electroluminescence experiments were also used to confirm the existence of a piezoelectric field in the InGaN MQW LED. [ABSTRACT FROM AUTHOR]

Minority-carrier diffusion lengths of electrons and holes were measured in a GaN-based light-emitting diode using the electron-beam-induced current technique in the line-scan configuration. A theoretical model with an extended generation source and a nonzero surface recombination velocity was used to accurately extract the diffusion length of the p- and n-type layers. A minority-carrier diffusion length of L[sub n]=(80±6) nm for electrons in the p-type GaN layer, L[sub p]=(70±4) nm for holes in the n-type GaN:Si,Zn active layer, and L[sub n]=(55±4) nm for electrons in the p-type Al[sub 0.1]Ga[sub 0.9]N layer were determined. The results from this model are compared with two simpler and widely used theoretical models. © 2001 American Institute of Physics. [ABSTRACT FROM AUTHOR]