Research on quantum efficiency and photoemission characteristics of exponential-doping GaN nanowire photocathode

2020

Int J Energy Res

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Summary The field‐assisted method is proposed to increase electron capture of the GaN nanowire cathode. We deduce the photoemission or electron collection efficiencies of the field‐assisted uniform‐doping and exponential‐doping cathodes using the diffusion‐drift formula. Results show that the external electric field has a significantly better collection efficiency for uniform‐doping nanowire cathodes than that of exponential‐doping. In cathodes without a build‐in field, quantum efficiency and collection efficiency reached a maximum at incident angles of 65° and 45°, and field intensity of 0.1 and 0.7 V/μm, respectively. The external electric field also contributes to the polarization of GaN nanowires. The field‐assisted GaN NWAs (nanowirearray) cathode could improve the photoemission performance and are expected to be realized in the follow‐up experiment.

Section: Model and Derivationmentioning

confidence: 99%

Section: Model and Derivationmentioning

confidence: 99%

E_{in} ((), z) = \frac{italicdV ((), z)}{dz} = \frac{d k_{0} italicTln \frac{N_{0}}{N ((), z)}}{qdz} = \frac{d k_{0} italicTln \frac{N_{0}}{N_{0} \exp ((), - italicAz)}}{qdz} = - \frac{k_{0} T}{q} A .

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Section: Model and Derivationmentioning

confidence: 99%

({, \begin{matrix} {J_{1} = \overset{true¯}{P} D_{n} \int_{z = 0}^{z = H} \frac{\partial n (x, z)}{\partial x}|}_{x = 0} italicdz \\ {J_{2} = \overset{true¯}{P} D_{n} \int_{z = 0}^{z = H} \frac{\partial n (x, z)}{\partial x}|}_{x = d} italicdz \\ {J_{3} = \overset{true¯}{P} D_{n} \int_{x = 0}^{x = d} \frac{\partial n (x, z)}{\partial z}|}_{z = H} italicdx \\ J = J_{1} + J_{2} + J_{3} \end{matrix}) .

…”

Section: Model and Derivationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Comparison of quantum and collection efficiency of field‐assisted uniform‐doping and exponential‐doping GaN nanowire cathodes

2020

Int J Energy Res

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Enhancement of Electron Collection and Light Trapping of Inclined GaN and AlGaN Nanowire Arrays

Zhangyang

2021

Energy Tech

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The structural design of excellent absorption and electron collection is the main challenge of the nanowire array (NWA) photocathode. Herein, the light trapping and photoemission performance of GaN and graded compositional AlGaN‐inclined NWA are systematically researched. The finite‐difference time domain method (FDTD) is used to calculate the light absorption under different inclined angles and array spacings. The results show that the NWA with an inclined angle of 0.4°–0.6° has greater light‐trapping capacity, which obtains up to 97% light absorption at a wavelength of 267 nm. The inclined graded compositional AlGaN NWA with a built‐in electric field has better photoemission performance. The external electric field further improves the electron collection capacity of the NWA cathode. The inclined AlGaN NWA cathode with the best parameters θ = 0.6°, L = 180 nm, and Eout = 2 V μm−1 obtains a quantum efficiency of 47.57% and collection efficiency of 31.09%. The study of the inclined graded compositional AlGaN NWA cathode assisted by the electric field provides an effective method for further utilization of incident light and emitted electrons.

The effective light‐harvesting performance of graded compositional Al _x Ga _1−x N nano‐cone arrays photocathode for ultraviolet detector—A numerical investigation and simulation

Zhangyang

et al. 2020

Int J Energy Res

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A graded compositional Al x Ga 1−x N nanomaterial with a built-in electric field has been proposed to improve the quantum efficiency of the negative electronic affinity photocathode. When the graded compositional Al x Ga 1−x N nano-cone array is applied to the ultraviolet (UV) detector, it is necessary to improve the effective light absorption, which is high absorption in the UV short-wavelength and high sensitivity in the threshold wavelength. Therefore, the light absorption of nano-cone arrays with different feature sizes and geometrical properties is accurately calculated innovatively based on the finite-difference time-domain method. Studies show that a non-close-packed six-sided pyramid structure with a fill factor of 42.44% and a height of 1000 nm has an absorption spectrum that better satisfies the response characteristics of the UV detector. Surface reflection depends to a large extent on the transformation of the angle of incidence. The optical absorption properties of the graded compositional Al x Ga 1−x N nano-cone array provide flexibility and reference value for the improvement of the absorption coefficient and other parameters in the actual quantum efficiency experiment of the UV photocathode with built-in electric field, which can realize the highest sensitivity of various designed UV detector optical system.