Characterization of soft-X-ray detectors fabricated with high-quality CVD diamond thin films

Iwakaji, Yoko; Kanasugi, M.; Maida, Osamu; Takeda, Yasuhisa; Saitoh, Y.; Ito, Toshimichi

doi:10.1016/j.apsusc.2008.02.156

Cited by 15 publications

(6 citation statements)

References 9 publications

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“…The significant increase in the current signal with increasing bias voltage can be interpreted as described in previous reports [15][16][17][18] where the higher the bias voltage, the greater the charge collection in the device and hence the rapid rate of e-h recombination phenomenon can be overcome. However the dark current increases.…”

Section: I-v Characteristicsmentioning

confidence: 99%

The X-ray detection performance of polycrystalline CVD diamond with pulsed laser deposited carbon electrodes

Abdel‐Rahman

Lohstroh

Jayawardena

et al. 2012

Diamond and Related Materials

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Section: I-v Characteristicsmentioning

confidence: 99%

The X-ray detection performance of polycrystalline CVD diamond with pulsed laser deposited carbon electrodes

Abdel‐Rahman

Lohstroh

Jayawardena

et al. 2012

Diamond and Related Materials

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“…7,8 A diamond detector has superior physical properties to a Si detector. 2, 8 Therefore, a DAD detector can be a compact electron detector for SEM with small dark current and high gain. 9 Additionally, the leakage current and dark noise are small because of a wide gap energy ͑5.5 eV͒.…”

Section: Introductionmentioning

confidence: 99%

“…9 Additionally, the leakage current and dark noise are small because of a wide gap energy ͑5.5 eV͒. 8 To evaluate the sensitivity to electrons, a DAD current I DAD was measured with a focused electron beam irradiating on the DAD detector. 2 For diamonds, E e-h is estimated to be 13.3 eV.…”

Section: Introductionmentioning

confidence: 99%

Electron detection performance of diamond avalanche diode

Morishita

Ohshima

Hatano

et al. 2010

Journal of Vacuum Science &Amp; Technology B, Nanotechnology and Microelectronics: Materials, Processing, Measurement, and Phen

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The authors evaluated the electron detection performance of a diamond avalanche diode (DAD) detector. In the electrode region, the gain was uniformly about 103 with little noise. Meanwhile, an avalanche multiplication occurred locally. In the avalanche region, a total gain of 5×104 was obtained. In some regions where the electric field is regarded to be intensified, the avalanche multiplication gain was estimated to be approximately 100–300, and the signal-to-noise ratio (S/N) was nearly equal to 1. The DAD can be applied to an electron detector for a scanning electron microscope due to its high gain and small dark current. However, it is necessary to improve the S/N and homogenize the gain to use the DAD detector as an electron detector.

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“…An impact ionization mechanism due to field enhancement in the electrode edge was suggested as the reason for the photocurrent gain at high applied biases. 11 This field enhancement, however, is difficult to explain the increase in the photocurrent at the temperature from RT to 65°C, since the impact ionization will be suppressed monotonically due to phonon scattering at elevated temperatures. 12 Considering the facts that ͑i͒ a gain larger than unity appears at high biases ͑i.e., 32 V͒ and is accompanied by a slow time response, ͑ii͒ the gain decreases when the measurement temperature is above 105°C at high biases ͑i.e., 32 V͒, and ͑iii͒ the photocurrent shows no dependence on the DUV intensity or the measurement temperature at low biases ͑i.e., 5 V͒, we propose that the gain larger than unity is related to charge trapping at the metal/diamond interface during DUV illumination.…”

mentioning

confidence: 97%

“…8,11 In both cases, the ohmic contact was a prerequisite because charge injection led to the gain. In the present study, no post-annealing treatment was applied.…”

mentioning

confidence: 98%

Light intensity dependence of photocurrent gain in single-crystal diamond detectors

et al. 2010

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The authors report on the photocurrent gain in a diamond photodetector that has two nonohmic contacts connected back-to-back. This photocurrent gain strongly depends on both the deep-ultraviolet ͑DUV͒ light intensity and the applied voltage. In addition, the gain is accompanied by a slow response. The gain is observed to originate from a metal/diamond interface trap center. Numerical analysis discloses that the photocurrentvoltage characteristics follow thermionic-field emission tunneling at low DUV light intensity and fieldemission tunneling at high DUV light intensity. The deep traps are thought to produce a thin interface barrier layer at the metal/diamond interface under DUV illumination, which is responsible for the tunneling processes.The interest in the utilization of diamond for deepultraviolet ͑DUV͒ detection has been triggered due to its extreme properties and the progress in the development of high-quality single-crystal diamond layers. 1-5 An important issue for practical devices is to achieve high responsivity or photocurrent gain while maintaining a fast response time. The high responsivity is important for weak signal detection such as flame or chemical sensing and DUV imaging with reduced pixel size.One strategy to generate photocurrent gain is to utilize quantum well structures or to introduce deep bulk defects. 6,7 As for diamond photodetectors, the incorporation of boron in the homoepitaxial layer can greatly improve the responsivity. In that case, the boron in the epilayer and the nitrogen in the substrate were dominant factors in the photoresponse behavior due to the formation of a p-n junction at the interface. A huge photocurrent gain was obtained when the boron content in the epilayer was relatively high, which was explained in terms of deeply trapped carriers by the ionized nitrogen in the substrate. 7 Since such a gain mechanism is controlled by the carrier transport in the epilayer, the metal contact to the diamond layer must be the ohmic type or Schottky type in the forward bias mode. In fact, no photocurrent gain was observed in the devices in our previous work if the metal/ diamond contacts were the blocking type. 8 In this work, we report that photocurrent gain can be generated as the DUV light intensity increases in a homoepitaxial diamond photodetector with two nonohmic contacts connected back-toback. The transient photocurrent behavior at different biases and the temperature effect on the photocurrent gain are investigated to understand the gain mechanism.The diamond layer was grown on a high-pressure hightemperature type-Ib ͑100͒ substrate using a microwave plasma-enhanced chemical vapor deposition reactor, which makes it possible to deposit a diamond epilayer at a much higher speed than our previous system. Hydrogen and methane gases were fed for diamond growth. In this apparatus, a higher methane concentration with a CH 4 / H 2 flow ratio of 2% was applied to achieve a higher growth rate. The substrate was heated to 1000-1090°C by high power plasma during growth. The total pre...

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Characterization of soft-X-ray detectors fabricated with high-quality CVD diamond thin films

Cited by 15 publications

References 9 publications

The X-ray detection performance of polycrystalline CVD diamond with pulsed laser deposited carbon electrodes

The X-ray detection performance of polycrystalline CVD diamond with pulsed laser deposited carbon electrodes

Electron detection performance of diamond avalanche diode

Light intensity dependence of photocurrent gain in single-crystal diamond detectors

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