Investigation of the electronic properties of <i>in</i> <i>situ</i> annealed low-temperature gallium arsenide grown by molecular beam epitaxy

Yin, L.-W.; Ibbetson, J. P.; Hashemi, M.; Gossard, A. C.; Mishra, Umesh K.; Hwang, You Mi; Zhang, T.; Kolbas, R. M.

doi:10.1063/1.107125

Cited by 5 publications

(1 citation statement)

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“…As a result, we could effectively reduce dark current of GaN-MSM photodetectors by employing the LT-GaN layer. 31 We also found that the measured photocurrents were about the same for these two samples when the incident-light wavelength was ϭ 360 nm, as shown in curves e and f. Such a result also indicates that sample A has a higher photocurrent to dark-current contrast ratio and thus higher detection sensitivity in the UV region because the dark current of sample A was much smaller than that of sample B. When the incident-light wavelength was ϭ 400 nm, it was found that photocurrent and dark current were almost the same for sample B, as shown in curves c and d. This is due to the fact that almost no absorption will occur when the incidentphoton energy is smaller than the bandgap energy of the crystalline HT-GaN layer.…”

Section: Abstract: Lt-gan Dark Current Msm Uv Photodetectormentioning

confidence: 97%

Nitride-Based ultraviolet metal-semiconductor-metal photodetectors with a low-temperature GaN layer

Sheu

Kao

Lee

et al. 2003

Journal of Elec Materi

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vices. It is known that LT-GaN exhibits an ultrahigh resistivity, which cannot be reduced even with thermal annealing. Such a semi-insulating property makes LT GaN suitable to serve as the top layer of MSM photodetectors. By depositing a LT-GaN layer on top of an n-GaN layer, we should be able to achieve a high Schottky-barrier height at the metal/ semiconductor interface, reduce leakage current, and thus, improve the performance of a GaN-based MSM photodetector.The GaN samples used in this study were all epitaxially grown on c-face sapphire substrates by metal-organic chemical vapor deposition. 11-29 Trimethylgallium (TMGa) and ammonia (NH 3 ) were used as the source materials of Ga and nitrogen, respectively. After annealing the sapphire substrate at 1,100°C in an H 2 ambient to remove surface contamination, a 30-nm-thick LT-GaN nucleation layer was deposited onto the sapphire substrate at 550°C. It should be noted that measured resistivity of the LT GaN was larger than 10 9 ⍀/ٗ, which is the detection limit of our instrument. The temperature was then raised to 1,050°C to grow a 2-m-thick, high-temperature (HT) GaN-epitaxial layer. Typical room-temperature carrier concentration of this HT GaN-epitaxial layer was ϳ2 ϫ 10 16 /cm 3 . A 30-nmthick, LT-GaN top layer was then grown on top of the HT GaN at 550°C (sample A). For comparison, samples without the LT-GaN top layers were alsoThe GaN metal-semiconductor-metal (MSM) ultraviolet (UV) photodetectors with a low-temperature (LT)-GaN layer have been demonstrated. It was found that we could achieve a two orders of magnitude smaller, photodetector-dark current by introducing a LT-GaN layer, which could be attributed to the larger Schottky-barrier height between the Ni/Au metal contact and the LT-GaN layer. It was also found that photodetectors with the LT-GaN layer could provide a larger photocurrent to dark-current contrast ratio and a larger UV-tovisible rejection ratio. The maximum responsivity was found to be 3.3 A/W and 0.13 A/W when the photodetector with a LT-GaN layer was biased at 5 V and 1 V, respectively.

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Section: Abstract: Lt-gan Dark Current Msm Uv Photodetectormentioning

confidence: 97%

Nitride-Based ultraviolet metal-semiconductor-metal photodetectors with a low-temperature GaN layer

Sheu

Kao

Lee

et al. 2003

Journal of Elec Materi

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Effect of low-temperature-grown GaN cap layer on reduced leakage current of GaN Schottky diodes

2005

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Unidirectional bulk conduction and the anomalous temperature dependence of drift current under a trap-density gradient

Watanabe

2010

Phys. Rev. B

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Nonlinear drift conduction under a trap-density gradient is mathematically formulated. Semianalytical and numerical solutions demonstrate bulk-induced unidirectional current flow, i.e., rectification. The present theory is in excellent agreement with various experimental J-V characteristics ͑J: current density and V: applied voltage͒. At low V, the J-V characteristics are ohmic and bidirectional. As the injection increases, the J-V characteristics become nonlinear and exhibit unidirectionality under proper conditions. The major requirements for a large unidirectionality are the trap-density gradient G ӷ 1, an intermediate V, and not too large trap-filling factor ⌰, which requires the presence of acceptorlike traps. The unidirectional J-V characteristics due to the difference in trap-filled-to-trap-free-limit voltage V TFL for forward and reverse bias markedly resemble the standard rectification. In addition, the trap-density gradient yields a positive T dependence of resistance for a proper set of parameters, evident J ϰ V 1.5 characteristics, and a photovoltaic effect. The present results suggest that bulk conduction under trap-density gradient explains fractions of resistance switching and rectification phenomena. The semianalytical solutions are verified by numerical solutions and comparison with experiments. In particular, semianalytical solutions for shallow-trap case excellently fit the experimental data by three parameters in practice: two scaling factors and G.

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Investigation of the electronic properties of in situ annealed low-temperature gallium arsenide grown by molecular beam epitaxy

Abstract: Articles you may be interested inIn situ and ex situ spectroscopic investigation of low temperature grown gallium arsenide by molecular beam epitaxy

Cited by 5 publications

References 5 publications

Nitride-Based ultraviolet metal-semiconductor-metal photodetectors with a low-temperature GaN layer

Nitride-Based ultraviolet metal-semiconductor-metal photodetectors with a low-temperature GaN layer

Effect of low-temperature-grown GaN cap layer on reduced leakage current of GaN Schottky diodes

Unidirectional bulk conduction and the anomalous temperature dependence of drift current under a trap-density gradient

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