Transitions in polycrystalline diamond probed by steady state, modulated and transient surface photovoltage spectroscopy

Abstract

Abstract Numerous electronic transitions in polycrystalline chemical vapor deposition diamond with characteristic nucleation and growth sides were obtained by highly sensitive surface photovoltage (SPV) spectroscopy in dc (Kelvin probe), ac (modulated) and ac (transient) regimes from near infrared to deep ultraviolet. In the dc regime, defect transitions D1 to D8 were detected at 0.8–0.9, 1, 1.37, 1.78, 2.27, 3.15, 4.2 and 5.42 eV, respectively. Hints for more transitions were found for measurements in the ac (modulated) regime in the range near D3. SPV measurements in the ac (transient) regime showed the importance of disorder for relaxation of SPV signals excited at different photon energies. Phonon assisted transitions were observed at E g− E x− hν LA,LO, E g− E x + hν LA,LO and E g− E x + hν TO. The developed SPV techniques are suitable for applications in research and quality control not only for diamond but also for any other semiconductor with ultra-wide bandgap.