Study Of GaAs:Si:Cu Material Properties For Optically Controlled Photoconductive Semiconductor Switch

Optically controlled photoconductive semiconductor switch (PCSS) has expansive prospect in the fields of high-power communities, pulsed power energy storage system, impulse radar and microwave communities. The conductivity of PCSS is increased or reduced, respectively, through illumination with light of different wavelengths, which corresponds to turning on or off for the switch. The increase in conductivity is accomplished by electron ionization from deep centers into the conduction band. The reduction of conductivity is obtained by hole ionization from the excited deep centers into the valence band and subsequent recombination with the free electrons. Theoretically, Siic2n (Si)-doped, Copper (Cu)-compensated GaAs (GaAs:Si:Cu) has excellent properties for PCSS: high-speed, jitter-free response, high frequency and so on. GaAs:Si:Cu-based PCSS can be exactly and rapidly turned on or off, and can sustain on-state conductivity without external energy complemented because of the particular characteristics of the deep level Cu B introduced by Cu. Therefore, GaAs:Si:Cu is the excellent material for PCSS. A systematic study on the properties of the material, including the mechanism of PCSS, the impurities or the defects that influence the on-state conductivity, the factors determine the rising and dropping time, the affection of the impurities?density and the laser wavelength and the photon flux on the conductivity, is essential for designing and fabricating PCSS. GaAs:Si:Cu material properties are studied in this paper for the sake of providing available information for developing the devices of the optically controlled photoconductive semiconductor switches. Copper is one of the frequent transition metal impurities in III-. V compounds III I.? ?~ and one of the most studied acceptor in GaAs. GaAs:Si:Cu switch can perform through the deep level introduced by Cu. The doping of shallow donor Si is to compensate the Cu deep level at thermal equilibrium. Because the Si and Cu concentration or their ratio and the photon flux are likely to influence the photoconductive features, the GaAs PCS S抯 photoconducting characteristics were simulated on the computer, the results show that the density ratio (N0~ I N~1) and the photon flux are two important factors that influence the properties of PCSS. Developing the GaAs:Si:Cu material includes copperiz.ing on the GaAs surface and diffusing Cu into the GaAs sample. Vaporizing, electroplating and spsttering are the common methods of plating Cu on the GaAs surface. But these methods are only fit for the mass-production because of the contamination to the working space. A chemical method was presented for the sake of the few-production of the scientific research for the first time, by which the Cu layer was deposited on the surface of GaAs sample. The method is simple and be able to yield uniform and glossy surface of deposited Cu layer, with strong attachment and high purity up to 99.99%, and the thickness can meet the request of unlimited source diiThse easily. The control of the Cu density plays a crucial role on the photoconductive characteristics of the GaAs switch. While the Cu concentration diffused into GaAs depends on the diffusing condition. Therefore, the experiments diffusing Cu into...