Semipolar (11–22) AlN Grown on m-Plane Sapphire by Flow-Rate Modulation Epitaxy for Vacuum-Ultraviolet Photodetection

Yang, Jiankun; Gao, Yaqi; Zheng, Wei; He, Rui; Huo, Ziqiang; Ji, Xiaoli; Ran, Junxue; Duan, Ruihong; Wang, Junxi; Li, Jinmin; Wei, Tongbo

doi:10.1021/acs.cgd.1c01320

Cited by 11 publications

(10 citation statements)

References 38 publications

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“…The root-mean-square (RMS) roughness of samples A′, B′, and C′ are measured as 4.91 nm, 2.99 nm, and 2.19 nm, respectively. It can be found that AlGaN samples B′ and C′ have typical undulated surface morphology, which can be explained by the increased anisotropic diffusion lengths of group III atoms and in-plane residual strain on the semipolar (112̅2) surface. , …”

Section: Results and Discussionmentioning

confidence: 98%

“…It can be found that AlGaN samples B′ and C′ have typical undulated surface morphology, which can be explained by the increased anisotropic diffusion lengths of group III atoms and in-plane residual strain on the semipolar (112̅ 2) surface. 24,25 It can be concluded that the improvement of the crystal quality of AlN template is helpful to obtain a high quality AlGaN epitaxial layer, according to the reflectance curves and the surface morphologies. These are consistent with the results previously reported by other researchers.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

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Semipolar (112̅2) AlGaN-Based Solar-Blind Ultraviolet Photodetectors with Fast Response

Gao

Yang

et al. 2022

ACS Appl. Mater. Interfaces

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The high-quality semipolar (112̅ 2) AlGaN epitaxial films have been obtained on m-plane sapphire by metal−organic chemical vapor deposition. X-ray rocking curve measurements show the full-width at halfmaximums of semipolar (112̅ 2)-oriented AlGaN films are 0.357°and 0.531°a long [112̅ 3̅ ] AlGaN and [11̅ 00] AlGaN , respectively. The fabricated semipolar AlGaN metal−semiconductor−metal solar-blind ultraviolet (UV) photodetector (PD) exhibits a high responsivity of 1842 A/W. The fast response and reliability of the UV PD are ensured via fast switching with a rise and decay time of 90 ms and 53(720) ms, respectively. The UV PD exhibits a significant reduction in the dark current, that is, from 100 μA to 780 fA at 10 V, using a simple wet chemical etching to modify the surface properties of materials. The photo-to-dark-current ratio value of the etched UV PD reaches 4 orders of magnitude higher than the unetched UV PD under 270 nm illumination. These are attributed to the fact that KOH wet etching assists in eliminating the surface states and reconstructing the surface oxides. This work might provide a new potential for the development of solar-blind UV PDs with high performance.

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Section: Results and Discussionmentioning

confidence: 98%

Section: ■ Results and Discussionmentioning

confidence: 99%

Semipolar (112̅2) AlGaN-Based Solar-Blind Ultraviolet Photodetectors with Fast Response

Gao

Yang

et al. 2022

ACS Appl. Mater. Interfaces

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“…The R of REG-AlN PD and DG-AlN PD are 2.23 and 1.33 A/W at 20 V, respectively, which are superior to the previous performance of VUV PD. 26,27 The external quantum efficiencies (EQEs) of REG-AlN PD are up to 25.3% at 10 V and 1 × 10 3 % at 20 V, respectively. From Figure 6c, it can be seen that the PDs have good repeatability in multiple optical on/off tests.…”

Section: Resultsmentioning

confidence: 99%

“…The dislocations of the semipolar AlN film along the [112̅3̅] AlN direction are mostly connected with F-S partial dislocations. The dislocations along the [11̅00] AlN direction are associated with the F-S partial dislocations, BSFs, and PSFs. ,, The FWHM (0002) of the off-axis was also measured to compare the crystal defects, which is associated with partial dislocations and/or perfect dislocations Figure a,b shows typical XRCs of semipolar (112̅2) AlN epitaxial films grown on m-plane sapphire before and after HTA.…”

Section: Resultsmentioning

confidence: 99%

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High-Temperature Annealing Assisted High-Quality Semipolar (112̅2) AlN Film for Vacuum Ultraviolet Detectors

Gao,

Yang,

Wang

et al. 2023

Crystal Growth & Design

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High-temperature annealing (HTA) has been recognized as an available method to annihilate the domain boundaries and improve the crystalline quality of AlN films. Here, semipolar (112̅2) AlN films through the HTA process are utilized to prepare the vacuum ultraviolet photodetectors (VUV PDs). The resulting semipolar AlN films show full widths at half-maximum of the high-resolution X-ray rocking curves that are 527 and 622 arcsec along [112̅3̅]AlN and [11̅00]AlN, respectively, which illustrates much improved crystalline quality compared to previous reports. HTA not only renders markedly improved AlN quality but also reduces the in-plane anisotropic characteristic. The responsivities of regrown AlN PD and direct-grown-AlN PD are 2.23 and 1.33 A/W at 20 V, respectively. The improvement in the responsivity and specific detectivity of PDs is attributed to the reduction of crystal mosaicity and stacking faults of semipolar (112̅2) AlN using HTA technology. These results have confirmed that the HTA strategy is significant for the improvement of semipolar (112̅2) AlN films and VUV PDs.

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Large‐Area Self‐Assembled Hexagonal Boron Nitride Nanosheet Films for Ultralow Dark Current Vacuum‐Ultraviolet Photodetectors

Zhang,

Li,

Chen

et al. 2024

Adv Funct Materials

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Hexagonal boron nitride (hBN) is one of the most promising candidates for vacuum‐ultraviolet photodetectors (VUV PDs). However, the efficient and low‐cost fabrication of large‐area hBN‐PDs still encounters challenges. Herein, a cost‐effective route is proposed for fast and scalable fabrication of high‐performance VUV PDs via hBN nanosheet (BNNS) films. BNNSs are peeled from bulk hBN and self‐assembled into large‐area ordered films. In such PDs, junction barriers are present at the contact interfaces of BNNSs and give the PDs a “light‐induced reduction of junction barrier height” working mechanism. The number of junction barriers are qualitatively adjusted by designing the size of BNNSs to optimize the performance of the devices. The performance of ultralow dark current (0.27 pA@80 V), high detectivity (3.42 × 1011 Jones), and fast response speed (20.97/17.69 ms) for 185 nm VUV light is achieved by a fabricated PD. Analysis based on the Schottky contact model proves that the large photoresponse is mainly attributed to the reduction of the barriers and series resistance on illumination. Meanwhile, a physical model is established to describe the working process of such PDs, of which conductivity is dominated by the junction barriers. Besides, a flexible PD is also fabricated, depicting excellent stability, and robustness.

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Semipolar (11–22) AlN Grown on m-Plane Sapphire by Flow-Rate Modulation Epitaxy for Vacuum-Ultraviolet Photodetection

Cited by 11 publications

References 38 publications

Semipolar (112̅2) AlGaN-Based Solar-Blind Ultraviolet Photodetectors with Fast Response

Semipolar (112̅2) AlGaN-Based Solar-Blind Ultraviolet Photodetectors with Fast Response

High-Temperature Annealing Assisted High-Quality Semipolar (112̅2) AlN Film for Vacuum Ultraviolet Detectors

Large‐Area Self‐Assembled Hexagonal Boron Nitride Nanosheet Films for Ultralow Dark Current Vacuum‐Ultraviolet Photodetectors

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