研究目的
A comprehensive study of the GaN:C bulk samples grown by HVPE technology on AT-GaN seeds is reported. Spectroscopy of point centres was performed by combining time resolved photoluminescence (TR-PL), microwave probed photoconductivity (MW-PC) transient and pulsed-photo-ionization spectroscopy (PPIS) techniques, together with spectral steady-state PL (SS-PL) and transmission measurements. All the measurements were performed at room temperature. The dynamics of the non-radiative and radiative recombination dependent on the excess carrier density and carbon concentration has been revealed.
研究成果
The study provides a detailed analysis of the optical and electrical properties of carbon-doped HVPE-GaN, revealing the dynamics of carrier recombination and the impact of carbon doping on these processes. It identifies several carbon-related defects and evaluates their parameters, contributing to the understanding of GaN materials for high-power and high-frequency device applications.
研究不足
The study is limited to room temperature measurements, and the impact of temperature variations on the properties of GaN:C samples is not explored. Additionally, the identification of specific point defects is tentative and based on literature data, requiring further confirmation.
1：Experimental Design and Method Selection:
The study combines several contactless/optical techniques including TR-PL, MW-PC transient, PPIS, SS-PL, and transmission spectral measurements to analyze the bulk GaN samples grown by HVPE technology on AT-GaN seeds with different carbon doping levels.
2：Sample Selection and Data Sources:
The samples are ~400 μm thick GaN samples grown by HVPE on AT-GaN substrates, with different carbon doping levels (low-LD and high-HD).
3：List of Experimental Equipment and Materials:
Equipment includes a Perkin-Elmer LAMBDA?1050 spectrophotometer for transmission measurements, a 325 nm He-Cd laser for SS-PL, a Streak Camera and Time-Gated PL Detection techniques for TR-PL, and a microwave probed photoconductivity setup for MW-PC transients.
4：Experimental Procedures and Operational Workflow:
The procedures involve recording SS-PL spectra, TR-PL transients, MW-PC transients, and PPIS spectra to analyze the dynamics of non-radiative and radiative recombination, surface recombination velocity, and the impact of carbon doping on these properties.
5：Data Analysis Methods:
The analysis includes fitting the experimental data with theoretical models to extract parameters such as photon-electron interaction cross-sections, broadening factors due to electron-phonon coupling, and concentrations of different defect centres.
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