Peculiarities of pulsed laser deposition of thin InGaAsN films in an active background gas atmosphere

Abstract

III-V-N compounds are a promising class of solid solutions that have the prospect of being used in optoelectronic devices operating in a wide spectral range up to 3 μm, as well as for increasing the efficiency of photodetectors, lasers in fiber-optic communication lines and telecommunication systems. In this work, the features of various methods for obtaining new III-V-N semiconductor materials are investigated. Thin InGaAsN films were obtained by pulsed laser deposition on GaAs (100) and Si (100) substrates in an active ackground gas atmosphere. Pulsed laser deposition of thin InGaAsN films was carried out using an In 0.02 Ga 0.98 As target in an atmosphere of a highly pure argon-nitrogen mixture at a pressure of 2, 5, and 10 Pa. The source of laser radiation was an AYG:Nd3+ laser with a wavelength of 532 nm (second harmonic), laser radiation energy density of 2.3 J/cm2, pulse repetition rate of 15 Hz, and pulse duration of 10 ns. The substrate temperature was 350 °C, the deposition time was 60 minutes. It is shown that the surface of thin films is textured with microdroplets. It has been established that microdroplets on the surface of a thin film are formed by metallic indium. It has been established that the distribution of indium microdroplets over the film surface is mainly ordered in the form of lines. This phenomenon can be explained by the presence of misfit dislocations. The average size of microdroplets on the surface of the InGaAsN film on GaAs (100) was about 30 nm, and their density did not exceed 0.076 μm–2. For comparison, in films obtained on Si substrates at a pressure of 2 Pa, the highest microdroplet density was 0.26 μm –2.The lowest density of microdroplets on the surface (0.17 μm–2) was noted in samples of a thin film of InGaAsN on Si (100) obtained at a pressure of 10 Pa. It is noted that the intensity of the local phonon vibrational mode LVM InN at a frequency of 430 cm–1 increases with increasing pressure of the argon-nitrogen mixture during pulsed laser deposition in the Raman scattering spectra of InGaAsN films on Si. In the Raman spectra of InGaAsN films on Si, second-order phonon modes LVM InN and LVM GaN were detected at frequencies of 450 cm –1 about 470 cm–1, respectively. This confirms the presence of nitrogen in a thin InGaAsN film obtained by pulsed laser deposition. It is shown that an increase in the pressure of the argon-nitrogen gas mixture during pulsed laser deposition contributes to an increase in the nitrogen concentration in thin InGaAsN films on Si. It has been established that the nitrogen concentration in InGaAsN films obtained at a pressure of 10 Pa on GaAs (100) and Si (100) substrates differs insignificantly and amounts to 1.9 % and 1.8 %, respectively. The presented results will make it possible to create highly efficient photoelectric converters and photodetectors for the near and mid-infrared range up to 3 μm based on the obtained InGaAsN thin films.