Electrical and photoconductive properties of boron-doped potycrystalline diamond films
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The current-voltage (I-V) characteristics and time-dependence photoconductivity of the undoped and B-doped diamond films (DF's) before and after annealing were investigated. The boron and hydrogen concentration in diamond films were measured by means of nuclear reaction analysis (NRA) and the elastic-recoil detection (ERD) technique, respectively. The results show that induced boron atoms and hydrogen atoms affect the electrical and photoconductive properties of diamond films. During the annealing process, B concentration kept even, but H content decreased. For undoped diamond films, the escaping of H atoms has great effects on the electrical characteristics, but for B-doped samples, this effect decreases with the increase of B concentration.
I. INTRODUCTION During the last few years, great interest has been generated in diamond films because of the superior properties of diamond. Recently, Fujimori,1 Kamo and Yurimoto,2 and Okano et al? synthesized boron-doped (B-doped) diamond films by chemical vapor deposition (CVD), and investigated the doping characteristics of the diamond films. The successful deposition of the B-doped diamond films opened up the possibility of applying diamond films to electronics. There are also some reports about electronic properties and infrared (IR) properties of boron-doped diamond films,4""6 whereas reports concerning the photoconductive characteristics of diamond films of different B concentrations are few. In 1991, Jeng et al.9 reported the photoconductivity of diamond films in the visible region and found that the photocurrent produced by boron-doped samples was approximately an order higher than that by undoped samples. Vaitkus et al.10 observed a significant enhancement of the photosensitivity in the visible-near-infrared region of uv illuminated samples. We have successfully synthesized p-type semiconductor diamond films using B 2 O 3 as a boron source and examined them by Raman spectroscopy, x-ray diffraction, and scanning electron microscopy (SEM), which verified the films to be high-quality polycrystalline diamond films. We have also proved that these films are p-type diamond films by the Hall and Seebeck effects, and the resistivity of B-doped diamond films decreases when boron concentration in diamond films increases. Boron concentration was measured by nuclear reaction analysis (NRA).5'8 In this paper, we report detailed results on the electrical and timedependence photoconductive characteristics of diamond films of different boron concentration and investigate the effects of annealing on the electrical and optical properties of B-doped diamond films. Hydrogen and 2350 http://journals.cambridge.org
J. Mater. Res., Vol. 10, No. 9, Sep 1995 Downloaded: 25 Mar 2015
boron concentration in diamond films were measured by means of NRA and the elastic-recoil detection (ERD) technique, respectively. The effects of H and B atoms on the electrical and photoconductive properties are discussed. The results may be helpful for the application of diamond films to detector-based devices
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