Low-Electron-Energy Cathodoluminescence Study of Polishing and Etching Effects on the Optical Properties of Bulk Single-Crystal Gallium Nitride

Published

January 1, 2003

Author(s)

Larry Robins, B. Steiner, Norman Sanford, Carmen Menoni

Abstract

Low electron energy cathodoluminescence (LEECL) was used to examine polishing-induced damage in a bulk high-pressure grown GaN single-crystal platelet. The Ga-polarity face of the platelet was mechanically polished; chemically-assisted ion-beam etching (CAIBE) to a depth of 200 nm was performed on a portion of this face. Low-temperature (15 K) CL spectra of the polished-only and polished+CAIBE regions of the Ga-face were taken at 2.8 kV, 5.4 kV, and 10.6 kV (corresponding to average electron penetration depths of 19 nm, 56 nm, and 170 nm). The low-temperature CL spectrum of the unpolished, N-polarity face was taken at 10.6 kV. In the near-band-edge region, all the CL spectra from the Ga-polarity face show a narrow peak near 3.47 eV, ascribed to donor-bound exciton recombination, and several overlapping peaks at lower energy (3.1 eV to 3.4 eV), ascribed to defect-related levels or to donor-acceptor pair recombination. Functional curve-fitting analysis enabled deconvolution of the spectra into the sum of an asymmetric peak (the donor-bound exciton) and several symmetric Gaussian peaks (the lower energy, defect-related or donor-acceptor peaks). The linewidth of the donor-bound exciton peak decreased with increasing penetration depth, and also decreased on going from the polished-only to the polished+CAIBE region. The relative intensity of a defect-related peak at 3.325 eV showed a similar decreasing trend with increasing penetration depth or with CAIBE treatment. The LEECL results suggest that the thickness of the polishing damage layer is approximately 400 nm; the 200 nm CAIBE step is thus insufficient to completely remove the damage.

Proceedings Title

Proc., Mater. Res. Soc. Symp.

Volume

743

Conference Dates

December 2-6, 2002

Conference Location

Boston, MA, USA

Pub Type

Conferences

Keywords

chemically-assisted ion-beam etching (CAIBE), epitaxial, GaN, Low electron energy cathodoluminescence (LEECL)

Citation

Robins, L. , Steiner, B. , Sanford, N. and Menoni, C. (2003), Low-Electron-Energy Cathodoluminescence Study of Polishing and Etching Effects on the Optical Properties of Bulk Single-Crystal Gallium Nitride, Proc., Mater. Res. Soc. Symp., Boston, MA, USA (Accessed December 13, 2024)