Characterization of Local Carrier Dynamics in AlN and AlGaN Films using High Spatial- and Time-resolution Cathodoluminescence Spectroscopy
Abstract
In order to assess the impacts of structural and point defects on the local carrier (exciton) recombination dynamics in wide bandgap AlN and high AlN mole fraction (x) AlxGa1-xN films, high spatial- and time-resolution spatio-time-resolved cathodoluminescence (STRCL) measurement system was constructed by adopting a pulsed photoelectron (PE) gun that is excited using a femtosecond pulsed laser under a front-excitation configuration. The PE emission efficiency was increased by approximately an order of magnitude in comparison with that of the rear-excitation one. Accordingly, measurements of high signal-to-noise (S/N) ratio local cathodoluminescence (CL) spectra and time-resolved CL signals of AlN became possible. Another important achievement brought by the improved PE emission efficiency is that (S)TRCL measurement of slow decay components became possible, because the repetition rate of the excitation laser could be reduced using a pulse-picker (repetition rate reducer). Eventually, CL intensity mapping of the near-band-edge (NBE) emission of AlN became possible. We will use this STRCL system to correlate the radiative and nonradiative lifetimes with structural irregularities in the near future.
Document Details
- Document Type
- Technical Report
- Publication Date
- Oct 12, 2012
- Accession Number
- ADA577706
Entities
People
- Kouji Hazu
- Shigefusa F. Chichibu
Organizations
- Tohoku University