Optically and thermally detected deep levels in <i>n</i>-type Schottky and p+-n GaN diodes

Hierro, A.; Kwon, Daewon; Ringel, S. A.; Hansen, M.; Speck, James S.; Mishra, Umesh K.; DenBaars, Steven P.

doi:10.1063/1.126580

Cited by 138 publications

(115 citation statements)

References 13 publications

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“…2 Observation of the E c − 2.42, 2.64, and 3.30 eV deep levels at V G = −3.6 V strongly implies that they are associated with either the UID-GaN or GaN:Fe regions, or both. Ascribing the E c − 2.64 eV level with MOCVD GaN agrees with a previous C-DLOS and DLTS study of n-type GaN grown by MOCVD that observed a band gap state at E v + 0.87 eV/ E c − 2.64 eV, 11 for which gallium vacancyrelated defects were identified as a likely source. Similarly, a PICTS investigation of a MOCVD-grown GaN metalsemiconductor field effect transistor reported a deep level at E c − 2.67 eV.…”

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confidence: 89%

Quantitative observation and discrimination of AlGaN- and GaN-related deep levels in AlGaN∕GaN heterostructures using capacitance deep level optical spectroscopy

Armstrong

Chakraborty

Speck

et al. 2006

Applied Physics Letters

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Deep levels were observed using capacitance deep level optical spectroscopy ͑DLOS͒ in an AlGaN / GaN heterostructure equivalent to that of a heterojunction field effect transistor. Band gap states were assigned to either the AlGaN or GaN regions by comparing the DLOS spectra in accumulation and pinch-off modes, where the former reflects both AlGaN-and GaN-related defects, and the latter emphasizes defects residing in the GaN. A band gap state at E c − 3.85 eV was unambiguously identified with the AlGaN region, and deep levels at E c − 2.64 eV and E c − 3.30 eV were associated with the GaN layers. Both the AlGaN and GaN layers exhibited additional deep levels with large lattice relaxation. The influence of deep levels on the two-dimensional electron gas sheet charge was estimated using a lighted capacitance-voltage method.

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confidence: 89%

Quantitative observation and discrimination of AlGaN- and GaN-related deep levels in AlGaN∕GaN heterostructures using capacitance deep level optical spectroscopy

Armstrong

Chakraborty

Speck

et al. 2006

Applied Physics Letters

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“…A number of different defect levels has been demonstrated in GaN Schottky and p þ -n diodes. 53 Furthermore, it was proposed that in GaN, there is a deep quasicontinuous density-of-states distribution. 54 The abundance of defect states in p-GaN would consequently result in the appearance of a broad violet peak different from the usual blue emission.…”

Section: The Origin Of the Emission Peaksmentioning

confidence: 99%

ZnO nanorod/GaN light-emitting diodes: The origin of yellow and violet emission bands under reverse and forward bias

Chen

Fang

et al. 2011

Journal of Applied Physics

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Study of droop phenomena in InGaN-based blue and green light-emitting diodes by temperature-dependent electroluminescence Appl. Phys. Lett. 100, 153506 (2012) Silicon-nanocrystal resonant-cavity light emitting devices for color tailoring J. Appl. Phys. 111, 074512 (2012) Effects of energetic disorder on the low-frequency differential capacitance of organic light emitting diodes J. Appl. Phys. 111, 074506 (2012) Probing the electrode-polymer interface in conjugated polymer devices with surface-enhanced Raman scattering Appl. Phys. Lett. 100, 141907 (2012) Low-cost caesium phosphate as n-dopant for organic light-emitting diodes J. Appl. Phys. 111, 074502 (2012) Additional information on J. Appl. Phys. ZnO nanorods have been prepared by electrodeposition under identical conditions on various p-GaN-based thin film structures. The devices exhibited lighting up under both forward and reverse biases, but the turn-on voltage and the emission color were strongly dependent on the p-GaN-based structure used. The origin of different luminescence peaks under forward and reverse bias has been studied by comparing the devices with and without ZnO and by photoluminescence and cathodoluminescence spectroscopy. We found that both yellow-orange emission under reverse bias and violet emission under forward bias, which are commonly attributed to ZnO, actually originate from the p-GaN substrate and/or surface/interface defects. While the absolute brightness of devices without InGaN multiple quantum wells was low, high brightness with luminance exceeding 10 000 cd/m 2 and tunable emission (from orange at 2.1 V to blue at 2.7 V, with nearly white emission with Commission internationale de l'éclairage (CIE) coordinates (0.30, 0.31) achieved at 2.5 V) was obtained for different devices containing InGaN multiple quantum wells.

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“…Further details of the test structure and fabrication can be found elsewhere. 9 B. Current-voltage-temperature "I-V-T… measurements and analysis I-V-T measurements were performed in the dark using a cryostat capable of temperatures from 85 to 400 K. I-V characteristics were obtained with an HP 4145B after the temperature stabilized in increments of 10 K. The ideality factor and saturation current parameters were extracted from the linear regime of the forward bias I-V characteristic, which for these diodes spanned between four and eight decades of linearity. The standard diode equation used to extract the I-V parameters is…”

Section: A Sample Preparationmentioning

confidence: 99%

Effect of threading dislocation density on Ni∕n-GaN Schottky diode I-V characteristics

Arehart

Moran

Speck

et al. 2006

Journal of Applied Physics

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The impact of threading dislocation density on Ni/ n-GaN Schottky barrier diode characteristics is investigated using forward biased current-voltage-temperature ͑I-V-T͒ and internal photoemission ͑IPE͒ measurements. Nominally, identical metal-organic chemical vapor deposition grown GaN layers were grown on two types of GaN templates on sapphire substrates to controllably vary threading dislocation density ͑TDD͒ from 3 ϫ 10 7 to 7 ϫ 10 8 cm −2 . I-V-T measurements revealed thermionic emission to be the dominant transport mechanism with ideality factors near 1.01 at room temperature for both sample types. The Schottky barrier heights showed a similar invariance with TDD, with measured values of 1.12-1.13 eV obtained from fitting the I-V-T results to a thermionic emission-diffusion model. The I-V-T results were verified by IPE measurements made on the same diodes, confirming that the Ni/ n-GaN barrier heights do not show a measurable TDD dependence for the TDD range measured here. In apparent contrast to this result is that the measured forward bias I-V characteristics indicate a shift in the observed forward bias turn-on voltage such that at the higher TDD value investigated here, a larger turn-on voltage ͑lower current͒ is observed. This difference is attributed to localized current blocking by high potential barrier regions surrounding threading dislocations that intersect the Ni/ GaN interface. A simple model is presented that reconciles both the observed voltage shift and variations in the extracted Richardson constant as a function of threading dislocation density. With this model, an average local barrier surrounding dislocation of ϳ0.2 V is obtained, which diverts current flow across the forward biased Schottky interface to nondislocated regions.

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Optically and thermally detected deep levels in n-type Schottky and p+-n GaN diodes

Abstract: Articles you may be interested inInterface trap characterization of atomic layer deposition Al2O3/GaN metal-insulator-semiconductor capacitors using optically and thermally based deep level spectroscopies

Cited by 138 publications

References 13 publications

Quantitative observation and discrimination of AlGaN- and GaN-related deep levels in AlGaN∕GaN heterostructures using capacitance deep level optical spectroscopy

Quantitative observation and discrimination of AlGaN- and GaN-related deep levels in AlGaN∕GaN heterostructures using capacitance deep level optical spectroscopy

ZnO nanorod/GaN light-emitting diodes: The origin of yellow and violet emission bands under reverse and forward bias

Effect of threading dislocation density on Ni∕n-GaN Schottky diode I-V characteristics

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