Surface recombination of hexagonal GaN crystals

Abstract

The influences of the surface recombination on the emission properties of the freestanding GaN with different polarity (+c and –c orientations) and forms were investigated. The time‐resolved photoluminescence measurements for the GaN pieces fabricated by cleaving the substrate indicated that the increase in surface/volume ratio leaded to the increase in the surface recombination rate even at low temperature. The excitation power density dependent photoluminescence measurements on as‐received and buffered hydrofluoric acid treated c ‐plane GaN surfaces indicated that the surface band bending was closely related to the surface recombination processes. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Electron‐beam incident‐angle‐ resolved cathodoluminescence studies on bulk ZnO crystals

“…Indeed, Xray photoelectron spectroscopy analysis has exhibited [10] that the spontaneous polarization induces upward band bending toward a Zn-polarity (+c) surface and downward but weaker band bending toward an O-polarity (-c) surface. Accordingly, previous analyses using steady-state and time-resolved photoluminescence (PL) measurements have confirmed [11,12] that the spontaneous polarizationinduced electric field (F spon ) affects the surface recombination in the c-planes of ZnO-based materials.…”