A Method for Fabricating Ultrafast Response Gan Photoconductive Switch Using Proton Irradiation

Abstract

The invention discloses a method for using proton irradiation to prepare an ultrafast response GaN photoconductive switch. The method uses proton beams as irradiation sources, and adopts two proton beams of different energy and fluence to radiate a GaN photoconductive switch device successively, thereby obtaining an ultrafast response characteristic. The prepared GaN photoconductive switch includes a sapphire substrate and a GaN layer, the GaN layer includes a AlN nucleating layer, a GaN high-temperature buffer layer, an i-GaN layer and an n-GaN layer, and a Ni / Cr / Au metal electrode is led out from the n-GaN layer. The proton irradiation conditions adopted by the invention are that the proton fluence is 1*10<11>~9*10<18> / cm2, and proton energy is 0.5~10 MeV. By use of the method, a response characteristic of a photoelectric conduction device can be obviously improved, an ultrafast response GaN photoconductive switch device can be prepared, and the method can be applied to the fields of ultrafast photoelectronics, large-power electromagnetic pulse generation and the like, and has great scientific value and broad application prospects.

Description

technical field [0001] The invention belongs to the field of ultrafast photoelectric detection, and relates to a photoconductive GaN semiconductor photoconductive switch (PCSS). Background technique [0002] Wide bandgap semiconductor materials such as GaN, SiC and diamond have excellent high-voltage resistance characteristics, especially GaN photoconductive switches are very suitable for high-voltage, high-power photoelectric conversion systems. More importantly, GaN as a direct band gap not only has a sub-picosecond response speed comparable to GaAs, but also has a high electron saturation rate (2.5×10 7 cm / s), high thermal conductivity (1.3W / cm K), and has a higher breakdown field strength (3.5x10 6 V / cm) and good linear working mode, it has very important research value and application prospect in the preparation of high reliability, fast response, high power solid-state photoelectric switch. [0003] The key performance requirements for photoconductive switches are: h...

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Problems solved by technology

[0005] However, Fe impurity doping also has the following problems: 1) The solid solubility of Fe atoms in GaN is only 0.4%. When the Fe doping concentration increases, it is easy to form Fe single crystal clusters, and it is also easy to combine with N Generate Fe-N nanoclusters (such as Fe 3 N), the quality of the film decreases, the surface is rough, and the crystal orientation becomes poor

The carrier scattering cross-section increases, resulting in a serious decrease in mobility and low on-state current of the device; 2) Fe atoms entering the lattice will replace the Ga atom position or fill the original Ga vacancy, and act as the main defect of Fe3+. After capturing electrons, it becomes Fe 2+ state, and then capture holes

And the more Fe doped, it will introduce more acceptor edge dislocations, and Fe 3+ There will be a self-compensation effect between them; and the more the Fe is doped, the more obvious the effect will be, resulting in a limited increase in the resistivity of GaN

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