Temperature-dependent emptying of grain-boundary charge traps in chemical vapor deposited diamond

Abstract

We have used the technique of ion beam induced charge with a 2 MeV He+ microprobe to image particle detectors fabricated from polycrystalline chemical vapor deposited diamond as a function of temperature. We find that detectors which display a thermally stimulated current peak at 190 °C display increased charge collection efficiency when heated above that temperature. The probability of detecting the impact of a single ion at room temperature was less than 2%, but this probability rises to over 80% at 170 °C. We model this effect by showing that charge trapped at grain boundaries is liberated at elevated temperatures and this results in an increased electric field within the detector volume and hence a raised charge collection efficiency.

A review of ion beam induced charge microscopy

“…The uniformity of charge response, temperature-dependent emptying of grain-boundary charge traps and the role of charge trapping at grain boundaries in CVD diamond [66][67][68] as well as polarisation and priming effects have been successfully investigated by IBIC, often in combination with other techniques, as PIXE [69], ion beam induced luminescence (IBIL) [70,71] or X-ray induced charge (XBIC) or light (XBIL) collection [72], providing valuable insights for the development of diamond detectors for tracking applications and for dosimetry [69]. Reviews of various IBIC applications in detectors and wide band gap semiconductors are given in [73,74].…”

Temperature-dependent hole detrapping for unprimed polycrystalline chemical vapor deposited diamond

“…Several techniques have been used to study the defect states in diamond; for example, Glesener 3 measured a boronrelated level with an activation energy of 0.29 eV in borondoped diamond using photoinduced current transient spectroscopy ͑PICTS͒. A wide range of deeper levels has been reported, including Gonon et al 4 and Hearne et al, 5 who reported activation energies of 1.86 and 1.1 eV, respectively, measured using thermally stimulated current technique ͑TSC͒. Bruzzi et al 6 reported a variety of defect levels in electronic-grade polycrystalline CVD diamond, with activation energies in the range 0.3-1.5 eV, observed using both TSC and PICTS.…”

Semiconductor Characterization by Scanning Ion Beam Induced Charge (IBIC) Microscopy

“…A model of charge trapping/recombination phenomena was proposed by Milazzo and Mainwood [72]. An efficient method to mitigate the effects of grain boundaries was proposed by Hearne et al [73], who showed that the charge collection efficiency of polycrystalline CVD diamond detectors increases with increasing temperature. When this trapped charge is released by heating the detector during the collection of induced charge, the local electric �eld becomes stronger and more uniform causing the charge collection efficiency to increase ( Figure 5).…”