Vacuum-semiconductor hybrid photodetector is a new kind of photoelectric detecting device. In this paper, the basic structure and principle of electron bombarded avalanche diode hybrid photodetector are introduced. Then a sample of electron bombarded silicon avalanche diode hybrid photodetector is successfully fabricated. The results show that the response range of the photodetector is 300nm-800nm, and the electron bombarded gain is more than 600 times under the high voltage of -8000V. The breakdown voltage of silicon avalanche diode avalanche is about -202V. The dark current of device under linear avalanche mode with gain equals 30 is about 3.2nA. The total gain of the tube after electron bombarded gain and avalanche gain are cascaded can be up to 1.5 × 104.
Based on the studies of the GaAs photocathode, the surface model of the InGaAs photocathode is investigated and the
energy distributions of electrons reaching the band bending region, reaching the surface and emitting into vacuum are
calculated. We use the quantum efficiency formula to fit the experimental curves, and obtain the performance parameters
of the photocathode and the surface barrier parameters. The results show that the electron escape probability is seriously
influenced by energy distribution and plays an important role in the research of high quantum efficiency as well. After
the theoretical calculation, the energy range of electrons crossing the BBR broaden, the peak of the electron energy
distribution shifts forward to low energy, the number of low energy electrons increases obviously; The surface barriers of
the InGaAs photocathode is similar to that of the GaAs photocathode. The height of barrier II not only decreases the
number of electrons, but also makes the width of electron energy distribution narrow. The prepared transmission-mode
InGaAs photocathode contains 20% InAs and 80% GaAs. This combination of InGaAs photocathodes is widely used in
the weak light detection field, such as night vision technology, forest fire prevention and harsh climate monitoring.
In order to avoid the low sensitivity common problem of 532nm sensitive narrow-band response photocathode, variable doping narrow-band response GaAlAs photocathode structure is designed. The photocathode is composed of GaAs substrates, Ga1-x1Alx1As buffer layer, Ga1-x2Alx2As doping concentration gradient emissive layer and GaAs protection layer from bottom to top. Among them, exponential doping method is applied to Ga1-x2Alx2As unit layer from the bottom to the top. And a preparation methods of GaAlAs photocathode is developed. For the GaAlAs photocathode components which grow well, chemical cleaning, heating purification and (Cs, O) activation are operated, and ultimately Cs / O activation layer is formed on the surface of Ga1-x2Alx2As doping concentration gradient emissive layer. The highest sensitivity of the photocathode peak response is at 532nm, and the photocathode quantum efficiency in 532nm peaks at 36%.
In order to obtain the suitable photocathode which could be applicable for the field of ocean exploration, the p-type zinc (Zn)-doped reflection-mode GaAlAs photocathode sample using exponential-doping technique is grown by metal organic chemical vapor deposition, the Al component of GaAlAs emission layer is designed to be 0.63. After the chemical etching, the photocathode samples are heated in vacuum at high-temperature of 650°C and 600°C respectively, the vacuum variation curves during the heat cleaning are measured, which correspond to the desorption of oxides in the surface of GaAlAs emission layer. The (Cs, O) activation for the photocathodes is executed after heat cleaning. Different proportion of Cs and O is performed on the different photocathode samples. The activation photocurrent curves of two samples with different heat cleaning temperature show that the GaAlAs surface treated by higher heat cleaning temperature is more sensitive to the Cs-O adsorption. The photocathode activated with the larger Cs current has a shorter time to reach the first photocurrent peak, and also obtains a bigger final photocurrent peak. According to the measured spectral response curves, it could be found that a suitable heat cleaning temperature and a moderate Cs/O current ratio are very important to prepare high performance GaAlAs photocathode. The prepared reflection-mode GaAlAs photocathodes are response to the blue-green light, and the cut-off wavelength is at about 580 nm.
A comparative study of semi-insulating GaAs substrate, p-Al<sub>x</sub>Ga<sub>1-x</sub> As/ semi-insulating GaAs and p-GaAs/p-Al<sub>x</sub>Ga<sub>1-x</sub>As/ semi-insulating GaAs structure has been done using the surface photovoltage (SPV) spectroscopy in metal–insulator–semiconductor (MIS) configuration. Which space charge region (SCR) dominated contribution to SPV in a certain wavelength range was determined. The SPV signals were calculated in a similar way as the open circuit voltage of an illuminated photodiode. One-dimensional continuity equations was adopted for determine the distribution of excess
minority carrier. The ideality factor of MIS configuration was investigated in air ambient. The contributions for SPV
signal of different layers were discussed in detail. At last the minority carrier diffusion length of different layers and
surface or interface recombination velocity were simulated.