Determination of the electron-capture coefficients and the concentration of free electrons in GaN from time-resolved photoluminescence

Reshchikov, M. A.; McNamara, J. D.; Toporkov, Mykyta; Avrutin, Vitaliy; Morkoç̌, H.; Usikov, A.; Helava, H.; Makarov, Yu.N.

doi:10.1038/srep37511

Cited by 43 publications

(77 citation statements)

References 26 publications

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“…The concentration of hydrogen is below the detection limit (2-5 × 10 17 cm −3 ) in these samples. Note that the total concentration of O and Si (which are shallow donors in GaN) in the bulk region is close to the total concentration of shallow donors determined from temperature-dependent Hall effect (about 1 × 10 17 cm −3 in all the samples) 17 . Table 1 summarizes the SIMS results for the C, O, and Si impurities.…”

Section: Resultssupporting

confidence: 75%

“…The UVL band is attributed to the Mg Ga defect 21 . The chemical identity of the RL1 band remains unknown, yet it is attributed to transitions from the conduction band (or from shallow donors) to a deep acceptor 17 . The transition level of this acceptor is located at 1.1-1.2 eV above the valence band.…”

Section: Resultsmentioning

confidence: 99%

“…2 is 10-20 µs (UVL), 290-520 µs (YL1), and 720-1600 µs (RL1), which corresponds to the concentration of free electrons in the range of (1.6−3.2) × 10 16 cm −3 according to the electron-capture coefficients found in ref. 17 . In contrast, the PL decay at T = 18 K is nonexponential, which is consistent with donor-acceptor pair (DAP) transitions involving shallow donors.…”

Section: Resultsmentioning

confidence: 99%

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Determination of the concentration of impurities in GaN from photoluminescence and secondary-ion mass spectrometry

Reshchikov

Vorobiov

Andrieiev

et al. 2020

Sci Rep

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photoluminescence (pL) was used to estimate the concentration of carbon in Gan grown by hydride vapor phase epitaxy (HVPE). The PL data were compared with profiles of the impurities obtained from secondary ion mass spectrometry (SiMS) measurements. comparison of pL and SiMS data has revealed that apparently high concentrations of C and O at depths up to 1 µm in SIMS profiles do not represent depth distributions of these species in the Gan matrix but are rather caused by post-growth surface contamination and knocking-in impurity species from the surface. in particular, pL analysis supplemented by reactive ion etching up to the depth of 400 nm indicates that the concentration of carbon in nitrogen sites is below 2-5 × 10 15 cm −3 at any depth of Gan samples grown by HVpe. We demonstrate that pL is a very sensitive and reliable tool to determine the concentrations of impurities in the Gan matrix.GaN is a key material in modern solid-state lighting technology. The investigation and identification of point defects in GaN is very important, with immediate technology relevance to longer lifetime of light-emitting devices. Photoluminescence (PL) is a powerful tool for investigation of point defects in GaN 1 . Only few point defects in unintentionally doped GaN are well understood and reliably identified. One of them is the C N defect with the −/0 and 0/ + thermodynamic transition levels at 0.916 eV and ~0.3 eV, respectively, above the valence band 2-5 . This defect is responsible for the yellow luminescence (YL1) band with a maximum at 2.2 eV and zero phonon line (ZPL) at 2.59 eV in n-type GaN. Transitions via the 0/ + level of this defect can be observed as the blue luminescence (BL C ) band with a maximum at 3.3 eV at high excitation intensity 4 . The YL1 band is commonly observed in n-type GaN layers grown by metalorganic chemical vapor deposition (MOCVD), where the concentration of unintentionally introduced carbon is usually in the range of 10 16 -10 18 cm −3 , depending on growth conditions 6,7 . Undoped or Si-doped GaN samples grown by hydride vapor phase epitaxy (HVPE) contain much less carbon (10 15 -10 16 cm −3 ) 8-11 , yet still the YL1 band may be strong in these samples due to high hole-capture cross-section for the C N defects 12 .We have recently demonstrated 12 that PL can be used for determination of concentrations of defects responsible for PL bands. However, the concentrations of impurities found from PL were inconsistent with the concentrations found from secondary-ion mass spectrometry (SIMS) analysis in that study. Comparison of these two techniques is complicated by the following ambiguity. SIMS measurements provide depth profiles of impurity concentrations regardless of positions of impurity species (lattice sites or precipitations), whereas PL signal, excited with above-bandgap light, is collected from impurity atoms at lattice sites in the near-surface region (roughly, top 0.4 µm layer in GaN). The problem is that close to the surface, where PL is collected, very high concentrations of carbon an...

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Section: Resultssupporting

confidence: 75%

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

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Determination of the concentration of impurities in GaN from photoluminescence and secondary-ion mass spectrometry

Reshchikov

Vorobiov

Andrieiev

et al. 2020

Sci Rep

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“…The time constant τ 3 = 1.68 ns is attributed to the carrier lifetime in the Mn IB states. Considering that the lifetimes of carriers in other defect-related states of GaN are on the μs timescale 32 , the lifetime of 1.7 ns in Mn IB states is relatively short. The timescale of ns is on the same order as the diffusion time of carriers in GaN 1, 26 .…”

Section: Resultsmentioning

confidence: 99%

“…Despite there is literature of carrier dynamics in GaN with different doping types 26–32 , lifetimes of carriers in Mn-doped GaN is unknown for applications of photovoltaics. The time-resolved information such as carrier lifetimes in each state are important for modeling 13 , because the absorption of photons within the forbidden gap is via the IBs as the step to generate free carriers.…”

Section: Introductionmentioning

confidence: 99%

Carrier dynamics of Mn-induced states in GaN thin films

Chen

Yang

Chen

et al. 2017

Sci Rep

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GaN-based materials are widely used for light emission devices, but the intrinsic property of wide bandgap makes it improper for photovoltaic applications. Recently, manganese was doped into GaN for absorption of visible light, and the conversion efficiency of GaN-based solar cells has been greatly improved. We conducted transient optical measurements to study the carrier dynamics of Mn-doped GaN. The lifetime of carriers in the Mn-related intermediate bands (at 1.5 eV above the valence band edge) is around 1.7 ns. The carrier relaxation within the Mn-induced bandtail states was on the order of a few hundred picoseconds. The relaxation times of different states are important parameters for optimization of conversion efficiency for intermediate-band solar cells.

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Influence of Temperature on Photodetection Properties of Honeycomb‐like GaN Nanostructures

Jain

Low

Vashishtha

et al. 2021

Adv Materials Inter

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image sensing, chemical analysis, and astronomy. These applications utilize a broad range of the solar spectrum from ultraviolet (UV) to infrared (IR) region. [1] Other applications such as flame and combustion monitoring, geothermal, mining, gas, and oil exploration require instrumentation capable of operating at elevated temperature conditions. [2] Conversely, applications such as research in the arctic region, space exploration, and cryostat based instrumentation require low-temperature operationality. [3] It demands a broadband photodetector, which should be functional under harsh temperature conditions covering low and high-temperature regions.Gallium nitride (GaN), being a direct wide bandgap material, is a promising semiconductor for power devices, radio frequency, analog devices, and optoelectronic devices. [4] It has high thermal and chemical stability making it a suitable candidate for photodetection devices operable under harsh temperature conditions. [5] Till date, most of the GaN photodetectors are tested at room temperature conditions, while the reports based on temperature correlated photodetection devices are limited to low responsivity values in both high and low-temperature regime. [6] Moreover, previous devices struggled with frosting at low temperatures due to their experimental setup. [6c,d] Besides, Broadband photodetectors operable under harsh temperature conditions are crucial optoelectronic components to support ongoing and futuristic technological advancement. Conventional photodetectors are limited to room temperature operation due to the thermal instability of semiconductors under harsh conditions and incapable of covering the ultraviolet (UV) spectrum due to narrow bandgap properties. Gallium nitride (GaN) is a wide bandgap and thermally stable semiconductor, ideal for addressing the abovementioned limitations. Here, epitaxial honeycomb nanostructured GaN film is grown via a plasma-assisted molecular beam epitaxy system and deployed for stable broadband photodetectors, which can be operated from −75 to 250 °C. Further, spectral response is investigated for a broad spectrum from UV (280 nm) to near-infrared (850 nm) region. It displays a peak responsivity at 365 nm associated to the bandgap energy of GaN. Fabricated photodetectors with honeycomb-like nanostructures drive peak responsivity and external quantum efficiency of 2.41 × 10 6 AW −1 and 8.18 × 10 8 %, respectively, when illuminated at a power density of 1 mWcm −2 and 365 nm wavelength source under 1 V bias. Temperature-correlated spectral response presents a quenching of responsivity at higher temperatures in visible spectrum associated with the thermal quenching of defect states. The thermally stable and efficient broadband photodetector based on honeycomb-like nanostructured GaN is promising for the combustion industry, arctic science, and space explorations.

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Determination of the electron-capture coefficients and the concentration of free electrons in GaN from time-resolved photoluminescence

Cited by 43 publications

References 26 publications

Determination of the concentration of impurities in GaN from photoluminescence and secondary-ion mass spectrometry

Determination of the concentration of impurities in GaN from photoluminescence and secondary-ion mass spectrometry

Carrier dynamics of Mn-induced states in GaN thin films

Influence of Temperature on Photodetection Properties of Honeycomb‐like GaN Nanostructures

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