Persistent photoconductivity in n-type GaN

Hirsch, M.; Wolk, J. A.; Walukiewicz, W.; Haller, E. E.

doi:10.1063/1.119738

Cited by 166 publications

(108 citation statements)

References 12 publications

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“…1 would also be expected to have small capture cross sections. Hirsch et al 13 confirm this, concluding from their PPC measurements that the trap corresponding to Trap 2 in the current work would need to have a very small capture cross section. With these considerations in mind, we choose a capture cross section of 1ϫ10 Ϫ18 cm 2 as an appropriate compromise to estimate (a/b) for Trap 2.…”

Section: ͑29͒supporting

confidence: 63%

“…In both cases the PPC studies were carried out on thick GaN layers grown on sapphire. 13,14 No conducting channel/HR GaN interface was present. It is therefore unlikely that the traps studied in this work, which we believe to be the same PPC centers, are located at the interface.…”

Section: Discussionmentioning

confidence: 99%

“…5. The concentrations of N Ϫ (t) ͑dashed line͒ and n(t) ͑solid line͒ are plotted versus illumination time for three values of the incident light flux; 5ϫ10 14 , 5ϫ10 13 , and 1ϫ10 13 cm Ϫ2 s Ϫ1 , which correspond to saturation, intermediate and linear regimes, respectively, for Trap 2 in the intensity dependent measurements shown in Fig. 2.…”

Section: ͑29͒mentioning

confidence: 99%

“…It was also noted 9 that these same traps are most probably associated with PPC effects as well, as each of the two spectra was found to reproduce the photoconductivity spectrum of a trap associated with PPC. 13,14 In order to study each trap individually through the dependence upon light intensity, a fixed wavelength was chosen for each trap. A wavelength of 600 nm ͑2.07 eV͒ was chosen for Trap 1 ͑see Fig.…”

Section: Photoionization Spectramentioning

confidence: 99%

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Photoionization spectroscopy of traps in GaN metal-semiconductor field-effect transistors

Klein¹,

Binari²,

Freitas³

et al. 2000

Journal of Applied Physics

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Measurements of the spectral and intensity dependences of the optically-induced reversal of current collapse in a GaN metal-semiconductor field-effect transistor ͑MESFET͒ have been compared to calculated results. The model assumes a net transfer of charge from the conducting channel to trapping states in the high-resistivity region of the device. The reversal, a light-induced increase in the trap-limited drain current, results from the photoionization of trapped carriers and their return to the channel under the influence of the built-in electric field associated with the trapped charge distribution. For a MESFET in which two distinct trapping centers have been spectrally resolved, the experimentally measured dependence upon light intensity was fitted using this model. The two traps were found to have very different photoionization cross-sections but comparable concentrations (4ϫ10 11 cm Ϫ2 and 6ϫ10 11 cm Ϫ2 ͒, suggesting that both traps contribute comparably to the observed current collapse. ͓S0021-8979͑00͒00417-5͔

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Section: ͑29͒supporting

confidence: 63%

Section: Discussionmentioning

confidence: 99%

Section: ͑29͒mentioning

confidence: 99%

Section: Photoionization Spectramentioning

confidence: 99%

See 2 more Smart Citations

Photoionization spectroscopy of traps in GaN metal-semiconductor field-effect transistors

Klein¹,

Binari²,

Freitas³

et al. 2000

Journal of Applied Physics

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“…Since the spectrometer's white light source is filtered only by the ZnSe window of the cryostat, photon energies up to 2.5 eV are available. As Ursaki, 19 Hirsch,20 and McCluskey 21 have pointed out, this is sufficiently large to release trapped electrons and holes from their midgap states into the conduction and the valence band, respectively. In addition, it has been observed by other groups that optical quenching takes place on a different, faster time scale than the persistent photoconductivity.…”

mentioning

confidence: 99%

Tunneling effects and intersubband absorption in AlN/GaN superlattices

Baumann

Giorgetta

Hofstetter

et al. 2005

Applied Physics Letters

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We report on intersubband absorption and photovoltage measurements on regular GaN/AlN-based superlattice structures. For barrier thicknesses larger than about 25 Å, the optical intersubband absorption peaks at a considerably smaller energy than the photovoltage spectrum. A simple model taking into account the oscillator strength of the involved transitions and the corresponding tunneling probabilities agrees with the experimental findings. According to this model, the observed photovoltage is the macroscopic manifestation that the two-dimensional electron gas at the top of the superlattice changes its carrier density by a vertical transport of electrons.Thanks to their large band gap energies, the semiconductor materials GaN and AlN have attracted a lot of attention for the fabrication of long-lived visible lasers and lightemitting diodes. 1-3 More recently, the huge conduction band discontinuity of nearly 2 eV between these two semiconductors has resulted in some device proposals based on intersubband transitions. [4][5][6] Particularly interesting in this context are photodetectors, modulators, or lasers in the technologically interesting 1.55 m wavelength range. Such devices could profit from short intersubband lifetimes, which might eventually result in high operating frequencies. 7,8 Unfortunately, the heavy effective masses of 0.2 m e for GaN and 0.32 m e for AlN impose the epitaxial growth of layer thicknesses in the 15-30 Å range, which, despite substantial progress in molecular beam epitaxy, is still quite a challenging task. 9

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