Carrier dynamics of Mn-induced states in GaN thin films

Chen, Yuting; Yang, Chih-Chyau; Chen, Po‐Cheng; Sheu, Jinn-Kong; Lin, Keng-hui

doi:10.1038/s41598-017-06316-7

Cited by 8 publications

(3 citation statements)

References 39 publications

(45 reference statements)

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“…Owing to the strong coupling of UV light and GaN nanoridge, the GaN nanoridge structure achieves a much stronger absorption intensity compared to that of planar GaN at 365 nm. Since GaN barely transmits UV light with wavelengths shorter than 365 nm, 58 the reduced reflectance directly leads to enhanced light absorption. Reflectance spectra of GaN nanostructures by MacEtch via dewetting times of 60, 120, and 240 s (Figure S3) are shown in Figure S8a.…”

Section: Resultsmentioning

confidence: 99%

Antireflective GaN Nanoridge Texturing by Metal-Assisted Chemical Etching via a Thermally Dewetted Pt Catalyst Network for Highly Responsive Ultraviolet Photodiodes

Liao

Kim

Lai

et al. 2023

ACS Appl. Mater. Interfaces

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Antireflective (AR) surface texturing is a feasible way to boost the light absorption of photosensitive materials and devices. As a plasma-free etching method, metal-assisted chemical etching (MacEtch) has been employed for fabricating GaN AR surface texturing. However, the poor etching efficiency of typical MacEtch hinders the demonstration of highly responsive photodetectors on an undoped GaN wafer. In addition, GaN MacEtch requires metal mask patterning by lithography, which leads to a huge processing complexity when the dimension of GaN AR nanostructure scales down to the submicron range. In this work, we have developed a facile texturing method of forming a GaN nanoridge surface on an undoped GaN thin film by a lithography-free submicron mask-patterning process via thermal dewetting of platinum. The nanoridge surface texturing effectively reduces the surface reflection in the ultraviolet (UV) regime, which can be translated to a 6-fold enhancement in responsivity (i.e., 115 A/W) of the photodiode at 365 nm. The results demonstrated in this work show that MacEtch can offer a viable route for enhanced UV light-matter interaction and surface engineering in GaN UV optoelectronic devices.

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Section: Resultsmentioning

confidence: 99%

Antireflective GaN Nanoridge Texturing by Metal-Assisted Chemical Etching via a Thermally Dewetted Pt Catalyst Network for Highly Responsive Ultraviolet Photodiodes

Liao

Kim

Lai

et al. 2023

ACS Appl. Mater. Interfaces

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“…Therefore, the carrier (electrons and holes) response should be taken care of when applying the transducer-less pump–probe thermoreflectance measurement. For the TL-TTR technique, using a nanosecond pulsed laser as the pump can avoid the non-thermoreflectivity effects from the carriers because the timescale of TTR response is from tens of nanoseconds to tens of microseconds while the excited carriers in GaN have decayed before then (the carrier relaxation and recombination processes occur on the sub-nanosecond time scale − ).…”

Section: Introductionmentioning

confidence: 99%

Transducer-Less Thermoreflectance Technique for Measuring Thermal Properties of the Buried Buffer Layer and Interface in GaN-based HEMTs

Yuan

Meng

Mao

et al. 2022

ACS Appl. Electron. Mater.

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Measuring the thermal properties of the buried GaN buffer layer and interface in GaN high-electron mobility transistor (HEMT) structures is of crucial importance. This remains challenging with the traditional pump−probe thermoreflectance techniques due to their limited thermal penetration depths and the difficulty in extracting the large number of unknown parameters in the multilayer HEMT structure. This work applies a transducer-less transient thermoreflectance technique (TL-TTR) for the characterization. We experimentally and numerically investigate the dynamic thermal transport process of the TL-TTR measurement, benchmarking against that of the traditional metal transducer transient thermoreflectance (MT-TTR) measurement. The significantly different heat absorption and dissipation processes in the two measurements lead to the distinctive measurement sensitivities. Notably, the sensitivity of TL-TTR signal to all unknown thermal properties follows a distinctive trend over the measurement time region, demonstrating the technique's capability of measuring the buried buffer thermal conductivity and the thermal boundary conductance (TBC) across the buffer/substrate interface. This is illustrated by measuring three different GaN-on-SiC wafers with highly Fe-doped buffer layers. The uncertainties of buffer thermal conductivity and TBC, determined by TL-TTR, are as low as ±6 and ±13%, respectively. In contrast, MT-TTR measures the buffer thermal conductivity and TBC with the uncertainties as large as ±20 and ±30%. The TL-TTR technique enables a non-invasive platform to characterize the thermal properties of the advanced GaN-based materials with complex structures and achieve a more in-depth understanding the phonon transport mechanisms.

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“…This intermediate band (IB) allows additional optical transitions, thereby enabling sub-band gap energy photons to contribute to the photocurrent by pumping electrons from the valence band (VB) to the IB and from the IB to the conduction band (CB). 17,18 Different approaches have been explored to implement the intermediate-band solar cell (IBSC) concept: (1) the use of highly mismatched alloys (HMAs), 19,20 a class of materials in which an isolated band is formed as a result of a band anti-crossing mechanism between the localized states of an isovalent dopant and the extended states of the host; 21,22 (2) the development of quantum dots solar cells (QDSCs) in which a periodic array of quantum dots introduce an IB in the fundamental gap of a suitable host; [23][24][25] (3) the use of heavily doped semiconductors [26][27][28][29][30] in which a suitable dopant introduces its d or s orbitals deep in the band gap, giving rise to a delocalized impurity-band. 17,31 Due to its wide band gap, ZnTe has been proposed as a good candidate for the development of intermediateband photovoltaic devices.…”

Section: Introductionmentioning

confidence: 99%

Defect properties of Sn- and Ge-doped ZnTe: suitability for intermediate-band solar cells

Flores¹

2017

Semicond. Sci. Technol.

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We investigate the electronic structure and defect properties of Sn-and Ge-doped ZnTe by first-principles calculations within the DFT+GW formalism. We find that (SnZn) and (GeZn) introduce isolated energy levels deep in the band gap of ZnTe, derived from Sn-5s and Ge-4s states, respectively. Moreover, the incorporation of Sn and Ge on the Zn site is favored in p-type ZnTe, in both Zn-rich and Te-rich environments. The optical absorption spectra obtained by solving the Bethe-Salpeter equation reveals that sub-bandgap absorptance is greatly enhanced due to the formation of the intermediate band. Our results suggest that Sn-and Ge-doped ZnTe would be a suitable material for the development of intermediate-band solar cells, which have the potential to achieve efficiencies beyond the single-junction limit.

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Carrier dynamics of Mn-induced states in GaN thin films

Cited by 8 publications

References 39 publications

Antireflective GaN Nanoridge Texturing by Metal-Assisted Chemical Etching via a Thermally Dewetted Pt Catalyst Network for Highly Responsive Ultraviolet Photodiodes

Antireflective GaN Nanoridge Texturing by Metal-Assisted Chemical Etching via a Thermally Dewetted Pt Catalyst Network for Highly Responsive Ultraviolet Photodiodes

Transducer-Less Thermoreflectance Technique for Measuring Thermal Properties of the Buried Buffer Layer and Interface in GaN-based HEMTs

Defect properties of Sn- and Ge-doped ZnTe: suitability for intermediate-band solar cells

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