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Superlattice component graded buffer layer transmissive algan ultraviolet photocathode and preparation method

A technology of composition gradient and buffer layer, which is applied in the direction of semiconductor devices, electrical components, circuits, etc., can solve the problem of not being able to effectively improve the photoemission performance of the transmissive AlGaN ultraviolet photocathode, affecting the short-wave response characteristics of the transmissive cathode, and reducing the buffer layer buffer layer and other issues to achieve the effect of improving photoemission quantum efficiency, increasing the number of electrons escaped, and reducing lattice mismatch

Inactive Publication Date: 2017-12-29
NANJING UNIV OF SCI & TECH
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Problems solved by technology

AlN material is usually used as the buffer layer. When the thickness of the cathode AlN buffer layer is 500nm, the absorption rate of the buffer layer to the incident light reaches 33.2%, which greatly reduces the short-wavelength photons in the transmissive AlGaN photocathode reaching the emission layer. Efficiency, which affects the short-wave response characteristics of the transmissive cathode
When the AlN crystal is 100nm, the absorption rate of incident light with a wavelength of 220nm is only 7.6%, but reducing the thickness of the buffer layer cannot ensure that the buffer layer has a relatively flat crystal surface, so a single AlN crystal structure is not effective as a buffer layer. Improving Photoemission Performance of Transmissive AlGaN UV Photocathode

Method used

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  • Superlattice component graded buffer layer transmissive algan ultraviolet photocathode and preparation method
  • Superlattice component graded buffer layer transmissive algan ultraviolet photocathode and preparation method

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preparation example Construction

[0015] The preparation method of the transmissive AlGaN ultraviolet photocathode of the superlattice gradient component gradient structure buffer layer of the present invention, the steps are as follows:

[0016] In step 1, the substrate layer 1 of the transmissive cathode is prepared with double-polished sapphire.

[0017] Step 2, using molecular beam epitaxy to grow 8-15 composition graded layers 11 on the sapphire substrate, and then growing a transition layer 12 on the surface of the uppermost composition graded layer 11, consisting of 8-15 composition graded layers 11 cyclic stacking and a transition layer 12 composed of superlattice gradient composition graded p-type Al x Ga 1-x N buffer layer 2. Each composition graded layer 11 is composed of 5-8 different compositions of Al from bottom to top x Ga 1-x Composed of N thin layers, where 0y Ga 1-y Consisting of N thin layers, where 0y Ga 1-y N emitter layer 3 is the same.

[0018] Step 3, use the molecular beam epitax...

Embodiment

[0022] Such as figure 1 As shown, the transmissive AlGaN ultraviolet photocathode of the superlattice gradient composition buffer layer of the present invention, the cathode is composed of a cathode transmissive substrate layer 1 (made of sapphire), a superlattice gradient composition gradient from bottom to top Structure Ga 1- x al x N buffer layer 2, p-type doped Ga 0.6 al 0.4 The N emission layer 3 and the Cs or Cs / O (cesium oxygen co-activation) active layer 4 are composed.

[0023] The superlattice gradient composition buffer layer is composed of 8-15 composition gradient layers 11 stacked circularly and a contact layer 12 with the emission layer, in which the six thin layer components of the composition gradient layer are: AlN 5, al 0.9 Ga 0.1 N6, Al 0.8 Ga 0.2 N 7, Al 0.7 Ga 0.3 N8, Al 0.8 Ga 0.2 N9 and Al 0.9 Ga 0.1 N 10, the composition of the 7 thin layers of the transition layer are: AlN 13, Al 0.9 Ga 0.1 N 14, Al 0.8 Ga 0.2 N 15, Al 0.7 Ga 0.3...

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Abstract

The invention discloses a superlattice graded buffer layer transmission-type AlGaN ultraviolet photoelectric cathode and a preparation method therefor. The photoelectric cathode consists of a substrate layer, a superlattice wedge graded p-type AlxGa1-xN buffer layer, a p-type AlyGa1-yN emission layer and a Cs or Cs / O activation layer from bottom to top, wherein the superlattice wedge graded p-type AlxGa1-xN buffer layer consists of 8-15 cyclically stacked graded layers and one transitional layer; the transitional layer is in contact with the emission layer; and the lowest graded layer is in contact with the substrate layer. According to the ultraviolet cathode and the preparation method, the growth quality of crystals is improved, the lattice defects in the buffer layer are reduced to a relatively large extent, the photon absorption rate of the emission layer is increased, and finally the photoelectric emission quantum efficiency of the photoelectric cathode is improved.

Description

technical field [0001] The invention belongs to the technical field of ultraviolet detection materials, in particular to a transmissive AlGaN ultraviolet photocathode of superlattice gradient composition gradient buffer layer and a preparation method. Background technique [0002] In recent years, with the improvement of AlGaN material preparation technology, p-type doping technology and the development of ultra-high vacuum technology, AlGaN ultraviolet photocathode is becoming a new type of ultraviolet photocathode. The surface of this photocathode has a negative electron affinity (NEA). Compared with the traditional positron affinity ultraviolet photocathode and solid-state ultraviolet detection devices, the AlGaN ultraviolet photocathode shows high quantum efficiency, small dark emission current, It has many advantages such as high ultraviolet-visible light suppression ratio, good stability, and concentrated energy distribution of emitted electrons, so it has great applic...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H01L33/36
CPCH01L33/36H01L2933/0016
Inventor 刘磊夏斯浩郝广辉常本康孔熠柯
Owner NANJING UNIV OF SCI & TECH
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