GaN-Based Metal–Semiconductor–Metal Ultraviolet Photodetectors with the ZrO<sub>2</sub>Insulating Layer

Chen, Chin-Hsiang; Tsai, Ying-Chien; Tsai, Sheng‐Han; Cheng, Chung-Fu

doi:10.7567/jjap.50.04dg19

Cited by 10 publications

(4 citation statements)

References 27 publications

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“…These limitations cause Schottky barrier inhomogeneity, , allow tunneling of carriers during reverse-bias conditions (in the dark), − ,, and trap or recombine the photogenerated carriers. , In addition to this, lowering of Schottky barrier height, due to surface electronic states on GaN, − is also responsible for allowing high reverse-bias current to flow in dark conditions, , thereby degrading the performance of the UV detector. Research has sought to alleviate these adverse effects by insertion of various oxide layers, such as Ta 2 O 5 , SiO 2 , ZrO 2 , Ga 2 O 3 , and HfO 2 , at the MS interface. − These metal–insulator–semiconductor UV PDs have shown reduced dark current, which is beneficial to some extent. But there are a few constrains.…”

Section: Introductionmentioning

confidence: 99%

Giant UV Photoresponse of GaN-Based Photodetectors by Surface Modification Using Phenol-Functionalized Porphyrin Organic Molecules

Garg

Tak

Rao

et al. 2019

ACS Appl. Mater. Interfaces

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Organic molecular monolayers (MoLs) have been used for improving the performance of various electronic device structures. In this work, the concept of organic molecular surface modification is applied for improving the performance of GaN-based metal–semiconductor–metal (MSM) ultraviolet (UV) photodetectors (PDs). Organic molecules of phenol-functionalized metallated porphyrin (hydroxyl-phenyl-zinc-tetra-phenyl-porphyrin (Zn-TPPOH)) were adsorbed on GaN, and Ni/Zn-TPPOH/GaN/Zn-TPPOH/Ni PD structures were fabricated. This process was beneficial in two ways: first, the reverse-bias dark current was reduced by 1000 times, and second, the photocurrent was enhanced by ∼100 times, in comparison to the dark and photocurrent values obtained for Ni/GaN/Ni MSM PDs, at high voltages of ±10 V. The responsivity of the devices was increased from 0.22 to 4.14 kA/W at 5 μW/cm2 optical power density at −10 V bias and at other voltages also. In addition to this, other PD parameters such as photo-to-dark current ratio and UV-to-visible rejection ratio were also enhanced. The spectral selectivity of the PDs was improved, which means that the molecularly modified devices became more responsive to UV spectral region and less responsive to visible spectral region, in comparison to bare GaN-based devices. Photoluminescence measurements, power-dependent photocurrent characteristics, and time-resolved photocurrent measurements revealed that the MoL was passivating the defect-related states on GaN. In addition, Kelvin probe force microscopy showed that the MoL was also playing with the surface charge (due to surface states) on GaN, leading to increased Schottky barrier height in dark conditions. Resultant to both these phenomena, the reverse-bias dark current was reduced for metal/MoL/GaN/MoL/metal PD structures. Further, the unusual photoconductive gain in the molecularly modified devices has been attributed to Schottky barrier lowering for UV-illuminated conditions, leading to enhanced photocurrent.

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Section: Introductionmentioning

confidence: 99%

Giant UV Photoresponse of GaN-Based Photodetectors by Surface Modification Using Phenol-Functionalized Porphyrin Organic Molecules

Garg

Tak

Rao

et al. 2019

ACS Appl. Mater. Interfaces

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“…For example, Lee et al used a 130 nm thick GaO x interlayer for achieving a photo‐to‐dark current ratio of ≈10 6 where a peak responsivity of 9 A W −1 was demonstrated. On the other hand, Chen et al reported a photo‐to‐dark current ratio of ≈10 3 using only a 30 nm thick insulating layer of ZrO 2 where a peak responsivity of only 0.02 A W −1 was reported. Yet, in another report, a photo‐to‐dark current ratio of ≈10 4 and a peak responsivity of 1.42 A W −1 were demonstrated by inserting a very thin (only 1.5 nm) layer of HfO 2 .…”

Section: A Summary Of Schottky Junction Parameters Estimated Using Thmentioning

confidence: 79%

“…Insertion of an insulating layer between metal and semiconductor is an effective technique for suppressing the leakage current and also for improving an overall performance of PDs. A significant reduction in the leakage current is already reported by several researchers by incorporating various insulating layers, such as SiO 2 , ZrO 2 , GaO x , and Al 2 O 3 . Although a considerable amount of work is already carried out on GaN‐based metal–insulator–semiconductor (MIS) PDs, a consensus among researchers is yet to arrive on the choice of material and thickness of the insulating layer.…”

Section: A Summary Of Schottky Junction Parameters Estimated Using Thmentioning

confidence: 99%

Role of ZrO₂ Passivation Layer Thickness in the Fabrication of High‐Responsivity GaN Ultraviolet Photodetectors

Chatterjee

Khamari

Porwal

et al. 2019

Physica Rapid Research Ltrs

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The importance of a ZrO2 passivation layer in the fabrication of high‐responsivity GaN‐based ultraviolet (UV) photodetectors (PDs) is discussed. It is found that an optimum thickness of the ZrO2 layer exists, which plays a critical role in controlling the photoresponse and transient response of the device. Beyond the optimal thickness, the performance of PDs deteriorates, which is limited by the restricted tunneling of photogenerated carriers across the oxide layer. At an optimum ZrO2 thickness of 3 nm, a spectral responsivity of 27 A W−1 at 361 nm is achieved at 4 V applied bias along with the fast response of the device with a rise (fall) time of 28 ms (178 ms), respectively. Such characteristics are found to be similar or better than the recently reported state‐of‐the‐art values for visible blind metal–semiconductor–metal PDs fabricated on GaN. The results confirm that the surface passivation with an optimal thickness of an oxide layer can be used to develop high‐responsivity GaN‐based UV PDs irrespective of having a large dark current, which is often inevitable due to the presence of a large density of dislocations in GaN epitaxial layers grown on foreign substrates.

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“…Typical structures of photodetectors include p-n junction [13], p-i-n photodiode [14], i-n structure [15], Schottky barrier (SB) [16], metal-oxide-semiconductor (MOS) [17], metal-semiconductor-metal (MSM) [18,19], and photoelectrochemical cell (PEC) [20] based structures [21,22]. Among various UV photodetectors made of 1D nanostructures, PECbased photodetectors show promising potential due to their low cost, simple fabrication process and fast response.…”

Section: Introductionmentioning

confidence: 99%

High-performance self-powered UV photodetectors based on TiO₂nano-branched arrays

Xie

Wang

et al. 2014

Nanotechnology

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Nano-branched TiO2 arrays were fabricated on fluorine-doped tin oxide (FTO) glass by a facile two-step chemical synthesis process. Self-powered UV photodetectors based on photoelectrochemical cells (PECs) were assembled using these TiO2 nano-branched arrays as photoanodes. These visible-blind self-powered UV photodetectors exhibit high sensitivity and high-speed photoresponse. Compared with photodetectors based on bare TiO2 nanorod arrays, TiO2 nano-branched arrays show drastically improved photodetecting performance as photoanodes. The photosensitivity increases from 0.03 to 0.22 A W(-1) when optimized nano-branched TiO2 arrays are used, corresponding to an incident photon-to-current conversion efficiency higher than 77%. The UV photodetectors also exhibit excellent spectral selectivity and fast response (0.05 s decay time). The improved performance is attributed to a markedly enlarged TiO2/electrolyte contact area and good electron conductivity in the one-dimensional, well-aligned TiO2 nanorod trunk.

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GaN-Based Metal–Semiconductor–Metal Ultraviolet Photodetectors with the ZrO₂Insulating Layer

Cited by 10 publications

References 27 publications

Giant UV Photoresponse of GaN-Based Photodetectors by Surface Modification Using Phenol-Functionalized Porphyrin Organic Molecules

Giant UV Photoresponse of GaN-Based Photodetectors by Surface Modification Using Phenol-Functionalized Porphyrin Organic Molecules

Role of ZrO₂ Passivation Layer Thickness in the Fabrication of High‐Responsivity GaN Ultraviolet Photodetectors

High-performance self-powered UV photodetectors based on TiO₂nano-branched arrays

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GaN-Based Metal–Semiconductor–Metal Ultraviolet Photodetectors with the ZrO2Insulating Layer

Cited by 10 publications

References 27 publications

Giant UV Photoresponse of GaN-Based Photodetectors by Surface Modification Using Phenol-Functionalized Porphyrin Organic Molecules

Giant UV Photoresponse of GaN-Based Photodetectors by Surface Modification Using Phenol-Functionalized Porphyrin Organic Molecules

Role of ZrO2 Passivation Layer Thickness in the Fabrication of High‐Responsivity GaN Ultraviolet Photodetectors

High-performance self-powered UV photodetectors based on TiO2nano-branched arrays

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Product

Resources

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GaN-Based Metal–Semiconductor–Metal Ultraviolet Photodetectors with the ZrO₂Insulating Layer

Role of ZrO₂ Passivation Layer Thickness in the Fabrication of High‐Responsivity GaN Ultraviolet Photodetectors

High-performance self-powered UV photodetectors based on TiO₂nano-branched arrays