Modelling of single-crystal diamond Schottky diodes for high-voltage applications S.J. Rashid a, * , A. Tajani c , L. Coulbeck b , M. Brezeanu a , A. Garraway b , T. Butler a , N.L. Rupesinghe a , D.J. Twitchen c , G.A.J. Amaratunga a , F. Udrea a , P. Taylor b , M. Dixon c , J. Isberg d a Department of Engineering, University of Cambridge, Trumpington Street, Cambridge CB2 1PZ, UK b Dynex Semiconductors Ltd., Doddington Road, Lincoln LN6 3LF, UK c Element Six Ltd., King’s Ride Park, Ascot, Berkshire SL5 8BP, UK d Division for Electricity Research, Box 539, S-751 21 Uppsala University, Sweden Available online 8 August 2005 Abstract The modelling of Schottky m-i -p + (SMIP) diodes fabricated on chemical vapour deposited (CVD) single crystal (SC) diamond intrinsic layers grown on highly boron doped CVD diamond substrates is reported. Variations in intrinsic layer thickness, Schottky metal type and operating temperature have been included in the analysis. Numerical models that take into account the activation of dopants, concentration and temperature dependant mobility and avalanche coefficients have been derived to successfully simulate experimental diamond devices. D 2005 Elsevier B.V. All rights reserved. Keywords: Diamond; Schottky diodes; Modelling 1. Introduction Recently, the use of diamond as a semiconductor for electronic devices has been the focus of much research. Apart from the fact that natural diamond is the hardest naturally occurring material, recent advances in growing synthetic single crystal (SC) chemical vapour deposited (CVD) diamond has highlighted the various outstanding electronic properties of the material. The outstanding material properties of diamond, namely its wide bandgap of 5.47 eV, high critical electric field (20 MV/cm) and carrier mobilities (4500 and 3800 cm 2 /V s for electrons and holes, respectively, in chemical vapour deposited (CVD) SSC type material) [1,2], exceed those of other wide bandgap materials (such as SiC and GaAs) which have also been proposed for power electronic devices. The constraint of higher power switching at high voltage linked to the physical limits of silicon is the main driver for the use of wide bandgap semiconductors such as GaN and diamond. Prospects for diamond as a semiconducting material are still at an exploratory stage and certain material parameters critical for characterising the performance of diamond devices have yet to be determined. In this work, we detail some of the models that have been taken into account to numerically analyse SC CVD diamond SMIP diodes. Results obtained from actual device fabrication are com- pared against results obtained from numerical modelling. 2. Device implementation The SC CVD diamond SMIP diode under investigation is shown in Fig. 1. It comprises of a highly boron doped 2  10 19 cm  3 p + substrate deposited onto a high temper- ature high pressure diamond substrate. A thin intrinsic layer is then grown on this p + substrate and polished down to the 0925-9635/$ - see front matter D 2005 Elsevier B.V. All rights reserved. doi:10.1016/j.diamond.2005.06.019 * Corresponding author. Tel.: +44 1223 332766; fax: +44 1223 332662. E-mail address: sjr64@eng.cam.ac.uk (S.J. Rashid). Diamond & Related Materials 15 (2006) 317 – 323 www.elsevier.com/locate/diamond