Single Schottky-barrier photodiode with interdigitated-finger geometry: Application to diamond

Liao, Meiyong; Koide, Yasuo; Alvarez, José

doi:10.1063/1.2715440

Cited by 107 publications

(59 citation statements)

References 14 publications

(16 reference statements)

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“…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.…”

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confidence: 97%

“…A tungsten carbide film with a thickness of 10 nm was deposited as the electrical contact. 8 The current-voltage ͑I-V͒ characteristics were measured using a two-point probe method with an Advantest picoammeter ͑R8340A͒ and a dc voltage source ͑R6144͒. A dc current mode was employed to record the spectral response, in which a 500-W Ushio xenon lamp and an Acton research monochromator with order sorting filters were used.…”

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

et al. 2010

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“…The development of innovative UV photodetectors has progressed considerably during the last years [2][3][4][5][6][7]. However, they are still under development and further improvements of their performance characteristics are still needed.…”

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Recent developments of wide-bandgap semiconductor based UV sensors

BenMoussa

Soltani

Schühle

et al. 2009

Diamond and Related Materials

103

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Future missions for space astronomy and solar research require innovative vacuum ultraviolet (VUV) photodetectors. Present UV and VUV detectors exhibit serious limitations in performance, technology complexity and lifetime stability. New developments of metal-semiconductor-metal (MSM) solar-blind photodetectors based on diamond, cubic boron nitride (c-BN), and wurtzite aluminium nitride (AlN) are reported. In the wavelength range of interest, the characteristics of the MSM photodetectors present extremely low dark current, high breakdown voltage, and good responsivity. Diamond, c-BN, and AlN MSM photodetectors are sensitive and stable under UV irradiation. They show a 200 nm to 400 nm rejection ratio of more than four orders of magnitude and demonstrate the advantages of wide band gap materials for VUV radiation detection in space.

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“…The growth conditions were described in the previous paper [5,6] as reported previously [4,5]. The gain mechanism is explained by existence of electron trap with high capture rate and low emission rate, which provides the significant increment of the hole lifetime and the hole concentration [3,6].…”

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“…Hence, an extremely robust material, which is stable under long-term or strong DUV illumination, is necessary for [3]. For example, the dark current can be extremely low due to the depletion of free holes in the submicron epilayer [4]. The threshold wavelength of the diamond detector can be tailored to be larger than 225 nm [4][5][6][7].…”

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Schottky photodiode using submicron thick diamond epilayer for flame sensing

et al. 2009

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The sensing of a flame can be performed by using wide-bandgap semiconductors, which offer a high signal-to-noise ratio since they only response the ultraviolet emission in the flame. Diamond is a robust semiconductor with a wide-bandgap of 5.5 eV, exhibiting an intrinsic solar-blindness for deep-ultraviolet (DUV) detection. In this work, by using a submicron thick boron-doped diamond epilayer grown on a type-Ib diamond substrate, a Schottky photodiode device structure-based flame sensor is demonstrated. The photodiode exhibits extremely low dark current in both forward and reverse modes due to the holes depletion in the epilayer. The photodiode has a photoconductivity gain larger than 100 and a threshold wavelength of 330 nm in the forward bias mode. CO and OH emission bands with wavelengths shorter than 330 nm in a flame light are detected at a forward voltage of -10 V. An alcohol lamp flame in the distance of 250 mm is directly detected without a focusing lens of flame light.

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Single Schottky-barrier photodiode with interdigitated-finger geometry: Application to diamond

Cited by 107 publications

References 14 publications

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

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

Recent developments of wide-bandgap semiconductor based UV sensors

Schottky photodiode using submicron thick diamond epilayer for flame sensing

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