Quantitative analysis of electronic absorption of phosphorus donors in diamond

摘要

In this work, phosphorus donors in diamond have been investigated by means of Fourier Transform Infra-Red (FTIR) transmission spectroscopy on a series of fully-characterized homoepitaxial layers. Low-temperature FTIR absorption spectra have been obtained for concentrations of donors in the range N-D = 3.7 x 10(16)- 3.5 x 10(18) cm(-3) and compensating acceptor impurities in the range N-A = 23 x 10(16)- 3.0 x 10(18) cm(-3). The absorption spectra is shown to exhibit two peaks at 4220 cm(-1) and 4540 cm(-1) corresponding to electronic transitions from the ground state to the 2p(0) and 2p(+/-) excited states, respectively, of phosphorus donors in the neutral state of charge. The intensity of the most intense peak at 4540 cm(-1) is found proportional to N-D-N-A over two decades. The absorption cross-section of the corresponding transition is deduced providing a calibration law for the determination of N-D-N-A in phosphorus-doped diamond. Furthermore, the linewidth of the peak exhibits a linear variation with the compensating acceptor concentration, interpreted as the effect of the distribution of ionized impurities. The use of the non-destructive and contact-less FTIR optical method is finally discussed to determine the compensation ratio in phosphorus-doped diamond. (C) 2017 Elsevier B.V. All rights reserved.