The MOCVD technology of III-Group nitrides deposition enabling the growth of semiconductor heterostructures for ultraviolet photodetectors is developed. The structures obtained are studied experimentally. High-speed photodetectors based on rectifying metal-semiconductor-metal (MSM) contacts are fabricated, and their performance is analyzed. The detectors are shown to exhibit low values of dark currents and high sensitivity within the range from 250 to 290 nm. Analysis of the spectral characteristics of the diodes shows that they can provide for solar-blind detection. The characteristics of the MSM detector pulse response are analyzed in terms of a simple model.

The effects of miniaturisation of optoelectronic devices makes simple size-scaling methods ineffective. A two-dimensional model demonstrates that the main problem in metal—semiconductor—metal (MSM) diode structures with small interelectrode gaps is the small depth of penetration of an electric field into the active region of a diode. This results in different rates of electron and hole collection at the contacts and delays the pulsed response of a photodetector. Self-consistent two-dimensional analysis is made of the photocarrier motion in the active region of an MSM diode structure and of the characteristics of the pulsed response of Ga0.47In0.53As MSM photodiodes. Ways of improving this response are discussed. The calculated results are compared with experiments.

The p+-cap layer of InP together with 80 nm of undoped (Nb equals 5 1014 cm-3) assist layer of InP for the first time were used to increase the Schottky barrier height (up to 0.73 e.V.) on GaInAs and to create high speed MSM photodetectors on it. The average dark current density is 1.6 10-4 A/cm2 -- the lowest known value on the GaInAs semiconductor material. A rise time of 37 ps for the impulse response at (lambda) equals 1.3 micrometers was measured for a MSM diode with 2 micrometers fingers and 2 micrometers gaps and an active area of 30 X 30 micrometers 2.

The use of epitaxial GaAs:Bi films doped with isovalent impurities ensured much better electrical characteristics of fast-response photodiode structures of the metal-semiconductor-metal type made from these films. In particular, the density of the dark current was lower, the coefficient representing the deviation of the current-voltage characteristics from the "ideal" behavior was smaller, and the avalanche breakdown voltage was higher. The use of such structures in various optoelectronic devices can improve their noise characteristics.

Current-voltage characteristics (CVC's) and photoelectric properties of Schottky barriers are studied in Al-GaAs/n-InGaAsP/i-InP structures obtained for the first time by a combination of two growth methods: liquid phase and molecular beam epitaxies. A layer of n-In0.59Ga0.41As0.88.P0.12 approximately 1-mu-m thick was grown on a {100} InP substrate by liquid phase epitaxy. An upper layer of GaAs approximately 0.2-mu-m thick was grown on the InGaAsP by molecular beam epitaxy. The height of the barrier formed between A1 and the heterostructure was 0.6-0.65 eV, which is congruent-to 0.1 eV higher than in an A1-InGaAsP structure without an upper GaAs layer. Structures were obtained in which shock ionization processes begin to develop only at bias voltages greater than 10 V. Studies of the photoelectric properties of the A1-n-GaAs/n-InGaAsP/i-InP revealed the presence of maxima in the region of n-GaAs intrinsic absorption (lambda = 0.5-0.9-mu-m) and the longwave region (lambda = 0.9-1.7-mu-m).