Quantum efficiency of heterostructured AlN/AlxGa1−xN photocathodes with graded bandgap emission layer

2020

Int J Energy Res

To obtain high-efficiency AlGaN monolayer photocathode, the quantum efficiency formulas of reflection-mode and transmission-mode Al x Ga 1 − x N monolayer photocathode with varying Al contents and ultra-thin emission layer are derived in this article. Based on the formulas, we have simulated quantum efficiency of Al x Ga 1 − x N monolayer photocathode under different conditions. The results reveal that built-in electric field caused by varying Al contents can significantly promote quantum efficiency of photocathode. If difference in Al contents between adjacent Al x Ga 1 − x N monolayer enlarges, quantum efficiency will decrease. At the same time, built-in electric field also plays a great impact in stabilizing quantum efficiency and photoelectric emission performance of Al x Ga 1 − x N monolayer photocathode. The ideal quantum efficiency and photoelectric emission performance can be obtained when buffer layer thickness is about 50 to 75 nm. In addition, when emission layer is composed of a larger number of Al x Ga 1 − x N monolayers with varying Al contents, the more number of monolayers with high Al contents are, the higher the quantum efficiency is. This study can give useful help for design and preparation of Al x Ga 1 − x N monolayer photocathodes with varying Al contents.

Section: Resultsmentioning

confidence: 99%

Section: Theoretical Models and Calculation Methodsmentioning

confidence: 99%

D_{i} \frac{d^{2} n_{i} ((), x)}{{italicdx}^{2}} - \frac{n_{i} ((), x)}{τ_{i}} + μ_{i} ∣ E ∣ \frac{{dn}_{i} ((), x)}{dx} + g_{i} ((), x) = 0

…”

Section: Theoretical Models and Calculation Methodsmentioning

confidence: 99%

E = \frac{E_{g} ((), {Al}_{x_{n}} {Ga}_{1 - x_{n}} N) - E_{g} ((), {Al}_{x_{1}} {Ga}_{1 - x_{1}} N)}{T_{n}}

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Section: Theoretical Models and Calculation Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Theoretical exploration of quantum efficiency ofAl_xGa_1 −xNmonolayer photocathode with varying Al contents and ultra‐thin emission layer

2020

Int J Energy Res

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

Zhangyang

2021

Energy Tech

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.

Photo-absorption and electron collection of field-assisted GaN nanohole array photocathode

J Mater Sci: Mater Electron

Zhangyang

2021

The light absorption and photo-generation rate under different periods, filling factors (FF), hole depth and inclination angles are studied. The NHA exhibits a larger light absorption compared with the planar film, which is about 99.99973%. Based on the three-dimensional continuity equation, the quantum efficiency (QE) and collection efficiency (CE) of the field-assisted GaN NHA and the graded compositional AlGaN NHA are calculated. The QE and CE of the GaN NHA with a period of 200 nm, a filling factor of 0.05, an inclined angle of 10°, and a field intensity of 2 V/μm are 62.7% and 62.6%, respectively. In addition, the graded compositional AlGaN structure has a more improved effect on the vertical NHA. Compared with the uniform GaN NHA, the electron collection of AlGaN NHA ratio is increased by 2.4 times. The design principles proposed in this work provide guidance to reasonable parameters for the application of NHA photocathodes.