This is a dataset of numerical data for experimental results of time-resolved cathodoluminescence and time-resolved photoluminescence of a HVPE-grown GaN sample, which are then de-noised and analyzed for estimating ABC recombination constants of this sample.
The examined GaN sample was prepared from a bulk crystal grown by Halide Vapor Phase Epitaxy (HVPE) method. In order to obtain a thick crystal, a few consecutive HVPE processes were performed. An ammonothermally-grown GaN seed of a very high structural quality, with the gallium surface prepared to an epi-ready state, was used in the first run. After the crystallization process the gallium surface of the new-grown crystal was prepared by mechanical and chemo-mechanical polishing to an epi-ready state. The crystal was used as the seed for the next HVPE run. The surface preparation and growth process were repeated until the crystal reached the required thickness. Finally, the ammonothermal seed was removed by slicing. The nitrogen side of the free-standing HVPE-GaN crystal was prepared by mechanical and chemo-mechanical polishing to an epi-ready state. The prepared sample was 1700-um-thick and of high structural quality.
The time-resolved cathodoluminescence measurements were conducted on an Allalin Chronos instrument from Attolight. In this tool, a focused electron beam scans the sample while the optical emission is collected and analyzed by a spectrometer. The spectrometer consists of a 320 mm monochromator (Horiba iHR320) fitted with a streak camera (Hamamatsu C10910) for TRCL measurements. During TRCL measurements, the electron beam is pulsed at 80 MHz using a laser focused on the Schottky field emission gun (FEG). TRCL measurements were performed at room temperature. Four beam energies were considered: 1.5 keV, 3 keV, 5 keV, and 10 keV. Ga-side and N-side surfaces were considered.
The time resolved luminescence and decay profiles were measured using apparatus which consists of a PG 401/SH optical parametric generator pumped by a PL2251A pulsed YAG:Nd laser (EKSPLA) with 30 ps laser pulses and a repetition rate 20 Hz. The detection part consists of a 2501S grating spectrometer (Bruker Optics) combined with a C4334-01 streak camera (Hamamatsu). Data were recorded in the form of the streak images on a 640 by 480 pixels CCD array. Software based on photon counting algorithm transforms the result into a 2D matrix of photon counts versus wavelength and time (streak image). The time resolve spectroscopic study was done for both sides of GaN monocrystal: Ga-side and N-side. The laser energy able to obtain 300 nm pulsed excitation wavelength was 30 mJ.
The experimental results are then de-noised by numerical scheme implemented in logpli software ( https://github.com/ghkonrad/logpli ). First, there is normalized luminescence intensity versus time, and then negative logarithmic derivative of the normalized luminescence intensity.
(2023)
