Free-Exciton Photoluminescence as a Probe of CVD Diamond (original) (raw)
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physica status solidi (a), 2007
ABSTRACT In this work time-of-flight (TOF) measurements are performed on freestanding single crystalline (100) CVD diamond layers with different surface terminations. The transit properties and electron and hole mobility are measured for completely oxidised and completely hydrogenated diamonds. The results clearly show that the different terminations of the diamond surface have an influence on the electrical transport properties. Furthermore, evidence is given that oxygen-induced surface states influence the TOF spectra. Light emission at 235 nm and around 430 nm is observed when applying a pulsed electric field on the diamond. The small peak at 235 nm is attributed to free exciton recombination while the broad band at 430 nm is contributed to A-band luminescence. Emission spectra at voltages as high as 1.4 V/μm are given and compared. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)
PHYSICAL REVIEW B 73, 245207 , 2006
We have adopted the transient-current technique as a sensitive method to detect small concentrations of charged defects in diamond and to study its photoionization spectrum. It is found that ionized impurity concentrations in the interval 109–1013 cm−3 can readily be detected in diamond. By continuously measuring the charge concentration, while illuminating the samples with monochromatic light, the evolution of the charge state of the dominating defect can be continuously monitored. We have obtained the photoionization crosssection spectrum from the dominant deep defect in single-crystalline chemical vapor deposition CVD diamond using this method. The photoionization spectrum exhibits an onset at photon energies above Ei =2.2 eV. It is also found that the defect is in the positively charged and acts as an electron trap. The observed spectrum can be attributed to the single substitutional nitrogen impurity.