Solar blind chemically vapor deposited diamond detectors for vacuum ultraviolet pulsed light-source characterization

Deep UV visible blind photoconductive devices can be fabricated on polycrystalline CVD diamond, a material that is intrinsically radiation hard and visible blind. However, the performance of detectors fabricated on as-grown material is insufficient to meet the requirements of many laserbased applications. In this paper, it is shown that sequentially applied post-growth treatments can progressively change both the gain and speed of these devices. Charge sensitive deep level transient spectroscopy (Q-DLTS) and transient photoconductivity (TPC) has been used to study the effect of these treatments on the defect structure of our thin film diamond detector material. For the first time, we report the successful operation of a diamond photoconductive device with linear bias and fluence response characteristics at more than 1 kHz at 193 nm.

Section: Resultsmentioning

confidence: 99%

High Speed Diamond Photoconductive Devices for UV Detection

Whitfield

Lansley

Gaudin

et al. 2001

“…Both the diamond devices are slower than the laser pulse. Since the carrier lifetime in CVD diamond is usually taken to be of the order of 0.1 ns [15], the device response time may be being influenced by the presence of traps. The behaviour of the slower device would appear to indicate a more significant trap density within the band-gap for this device.…”

Section: Resultsmentioning

confidence: 99%

Diamond Electronics: Defect Passivation for High Performance Photodetector Operation

Whitfield

Lansley

Gaudin

et al. 2000

Deep UV, visible blind, photoconductive devices fabricated on polycrystalline CVD diamond using inter-digitated planar electrodes have shown promising characteristics. The`as-fabricated' device performance is insufficient for many applications; a particularly demanding example is the monitoring of high power excimer lasers operating in the UV, which ideally require visible-blind, radiation hard fast UV detectors. However, post-growth treatments can strongly modify the performance level achieved. In this paper, we show that sequentially applied treatments can progressively change both the gain and speed of these devices. We have used charge sensitive deep level transient spectroscopy (Q-DLTS) to study the effect of these treatments on the defect structure of CVD material. For the first time, we report the realisation of diamond photoconductive devices capable of operating at more than 1 MHz at 193 nm.

“…This application thus combines requirements for high sensitivity, thickness, stability with respect to time, and uniformity -low energy X-ray sensitivity typ. 20% [28,37] of the sensitivity along the surface in thickness for electric field uniformity; the latter condition being reached from the mechanical polishing of the diamond layers. All these aspects are the frames of the RD42 collaboration at CERN [25] in close collaboration with industrial CVD diamond growers.…”

Section: Applicationsmentioning

confidence: 99%

Particle and Radiation Detectors Based on Diamond

Bergonzo

Tromson

Mer

et al. 2001

Self Cite

CVD diamond is a remarkable material for the fabrication of particle and photon radiation detectors. The improvement of the electronic properties of the material has been under intensive investigations and led to the development of a few applications that are addressing specific industrial needs. In particular, we have used diamond layers for industrial applications where it exhibits attractive characteristics as compared with other materials: e.g., radiation and corrosion hardness for a-counters or high gamma-meters at high fluxes; high transparency to low energy X-rays for synchrotron beam line monitoring devices, etc. These specific properties can motivate the use of diamond even though the detection properties remain relatively poor. Indeed, one inherent problem with diamond is the presence of defect levels that are altering the detection characteristics. These are observed in all CVD materials but also in very high quality natural diamonds. They result in unstable responses and carrier losses. Also, it has been observed that high sensitivities may result from the progressive filling of deep levels, e.g. pumping effects, with a detrimental effect on the stability and the response time. Also, the polycrystalline nature is somewhat detrimental as it induces significant non-uniformities of the device response with respect to the position of interaction. We have investigated these features by imaging the response of CVD diamond using a micrometer size focused X-ray beam. The comparison with the grain structure showed that it has a strong influence on the field distribution. We present here recent developments studied at CEA in Saclay for the optimisation of the material with respect to the specific requirements of several applications. They include radiation hard counters; X-ray intensity, shape and beam position monitors, solar blind photodetectors, and high dose rate gamma-meters.