NEA electron source for vertically emitting AlGaAs/GaAs nanowires

Abstract

The invention provides an NEA electron source for vertically emitting AlGaAs/GaAs nanowires. A p type GaAs is taken as a substrate layer, a variable-band gap AlGaAs emission layer of which the Al component is linearly and gradually reduced to zero from high to low, and a GaAs emission layer are orderly grown on the GaAs substrate layer, next, a variable-band gap AlGaAs/GaAs nanowire array emission layer is obtained by use of a reactive ion etching technique, and then Cs/O excitation is performed in an ultrahigh vacuum system so as to form a Cs-O activation layer on the variable-band gap AlGaAs/GaAs nanowire array emission layer; in addition, a built-in electric field is formed on the variable-band gap AlGaAs/GaAs nanowire array emission layer in the vertical direction, and the photoelectrons in the nanowires are controlled to directionally drift and be emitted by use of the built-in electric field, so that the photoelectric emission of the side surface can be effectively inhibited, and therefore, the application of the variable-band gap AlGaAs/GaAs material is expanded; the nanowire array structure is capable of improving the photoelectric emission efficiency.

Description

technical field [0001] The invention relates to the technical field of vacuum photoelectric emission materials, in particular to a NEA electron source for vertically emitting AlGaAs / GaAs nanowires. Background technique [0002] Negative electron affinity (NEA) electron source is a photocathode material that converts incident light into electron emission by using the external photoelectric effect. Negative electron affinity GaAs electron source has high quantum efficiency, small dark emission, and emitted electron energy It has many advantages such as concentrated angular distribution, high spin polarizability of emitted electrons, high emission current density, and uniform planar electron emission. It has been widely used in electron accelerators, free electron lasers, and high-end instruments and equipment. [0003] Traditional NEA electron sources are usually made of thin-film materials. However, due to the high reflectivity of thin-film materials, the transport distance o...

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Problems solved by technology

In 2010, Maite Volatier from the University of Sherbrooke, Canada, used inductively coupled plasma etching technology to prepare AlGaAs / GaAs nanowire waveguide structures with variable bandgap from 0 to 100% Al composition; in 2012, Anuj GaAs nanowire arrays were prepared by combining nanosphere etching and selective area metal-organic chemical vapor deposition by R.Madaria et al. In 2014, Paola Prete et al. of the Italian Institute of Microelectronics and Microsystems grew AlGaAs / GaAs cores by metal-organic chemical vapor deposition. -nanowire array with shell structure; at the same time, researchers at home and abroad have also explored its application in optical waveguides, light-emitting diodes, etc., but there has been no relevant report on the field of photoelectric emission electron sources

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