The development of lasers has stimulated the appearance of new technical fields such as optical communications, laser location, optoelectronic computers, and information systems. For all these fields the primary problem is detecting short (tens of nanoseconds and shorter) weak (hundreds, tens of photons) light pulses. Today this problem is being solved by photodetectors such as photomultipliers and avalanche photodiodes with the fast-response mechanism of internal gain: multiplication of carrier numbers by impact ionization.

Самостабилизированный лавинный процесс в структуре металл - диэлектрик - полупроводник (МДП). Лавинные МДП-фотоприемники, Басов Н.Г., Кравченко А.Б., Плотников А.Ф., Шубин В.Э.

A report is given of a theoretical and experimental investigation of the dynamics of the interaction between an avalanche process in a metal–insulator–semiconductor (MIS) structure and light. The case of a stable avalanche is considered in detail. The main transient effects responsible for the detection of light with the aid of pulsed avalanches are studied. A good agreement is obtained between the experimental results and a theoretical model. The results of the investigation make it possible to determine the potential applications of photodetectors in the form of MIS structures operating under avalanche conditions.

It is reported that a metal–insulator–semiconductor (MIS) structure, operating in the pulsed avalanche regime, can be used as the basis of a multielement high-sensitivity fast-response photodetector array for optoelectronic applications. The principal parameters are reported for a multielement array consisting of 20 structures with internal amplification.

A theoretical and experimental investigation was made of the dynamics of a pulsed avalanche process in a metal–insulator–semiconductor (MIS) structure. It was predicted that the application of a linearly rising voltage should produce a quasi-equilibrium avalanche. Full agreement was observed between the experimental results and the theoretical model. The principal differences in the dynamics of the avalanche process were established between an MIS structure and a p–n junction. The results indicated that it should be possible to use the avalanche effect in new optoelectronic photodetection systems.

A study was made of the possibility of using metal-insulator-semiconductor (MIS) structures with GaP–GaAs heterojunctions as electrically and optically controlled transparencies. The results obtained were used to estimate the attainable contrast and efficiency of these transparencies. Light pulses of 10–6 J/mm2 energy, produced by an He–Ne laser, were used to record a diffraction grating with a spatial frequency in excess of 180 lines/mm and a diffraction efficiency of 3×10–3.

An experimental study was made of switching in a metal-nitride-oxide-semiconductor (MNOS) structure with insulator layers formed by plasmochemical deposition on gallium arsenide substrates. Such switching was found to be of threshold nature. The switching by negative voltage pulses occurred only during illumination. The light pulse energy needed for switching was 2×10–6 J/mm2. The charge stored in the traps in the insulator decayed by less than 25% in a period of 20 h after switching.

An investigation was made of avalanche multiplication of carriers in the surface region of a metal–insulator–semiconductor (MIS) structure. Transient photocurrents resulting from such multiplication were observed in a surface layer of silicon in an Au–SiO2–Si structure. The results obtained indicated that avalanche multiplication of carriers in MIS structures could be used for detection of light.

A calculation was made of the illumination-induced redistribution of the voltage in the structure between the dielectric (combined nitride and oxide layers) and a surface depletion layer in the semiconductor (silicon). The relaxation time of the space charge in the semiconductor was determined experimentally during illumination of the structure.

An investigation was made of the spatial resolution achieved in optical recording of information using a metal-nitride-oxide-semiconductor (MNOS) structure with a continuous electrode. A resolution of at least 10 μ in photoelectric reading was achieved only when an additional dielectric-film grid was deposited below the continuous electrode. Six bits of information were recorded experimentally as separate points.

Two methods were developed for reading the potential relief obtained on pulse illumination of a metal-silicon nitride-silicon dioxide-silicon (MNOS) structure. The methods used were the measurement of the photoemf and of the photocurrent. The photocurrent method had several important advantages such as the absence of the dependence of the photocurrent signal on the charge state of neighboring parts of the structure and a higher (by more than two orders of magnitude) clock frequency in the information reading process. In both methods the spatial resolution was at least 10 μ. The energy characteristics obtained in reading at two wavelengths (0.9 and 0.63 μ) were reported.