Influence of the plume energy on the SnO$_2$:Sb films characteristics by using the PLD droplet-free method

Problem: Еhe films of the transparent conductive oxides widely are used as transparent high-conductivity thin-film materials for application in various areas, such as solar elements [1], gas sensors [2], optoelectronic devices, high-temperature mirrors [3] and flat panel displays. The tin oxide films alloyed by antimony possess higher thermal and chemical stability in comparison with, the oxide films india alloyed by tin, and also mechanical durability that allows them to maintain influences of environment at which solar elements work. Development of new optoelectronic devices on flexible substrates, and also devices of organic electronics makes increased requirements to quality and conditions of synthesis of such compounds: it is necessary to provide high coefficient of a transmission in visible area of the spectrum and low specific resistance at temperatures of substrate no more than 150$^o$C in the course of receiving. Receiving by method of the pulse laser deposition (PLD) in the droplet-free regime on substrates from quartz glass of thin films of SnO$_2$:Sb, under various conditions of deposition without the subsequent annealing and research of structural, electric and optical properties of the received thin films of SnO$_2$:Sb was the purpose of the real work.
Methodology: The PLD method has certain advantages in comparison with other methods of receiving thin multicomponent oxidic films. The composition of the films which are grown up by the PLD method thanks to nonequilibrium conditions of deposition, completely reproduces the composition of components of a target. The films received by the PLD method crystallize at lower temperatures of a substrate in comparison with other physical methods of steam deposition, thanks to high kinetic energy (>1 эВ) the ionized injected particles in the created laser plasma. Possibility of direction of a power spectrum of a plume allowed to investigate features of growth and direction of properties of the grown-up films.
Results: On substrates of quartz glass without the subsequent annealing thin films of SnO$_2$:Sb by method of pulse laser deposition with high-speed separation of particles are received under various conditions of deposition in the energy density range on a target from 3,4 J $\cdot$ cm$^{-2}$ to 6,8 J $\cdot$ cm$^{-2}$. The minimum of specific resistance 1,2 $\cdot$ 10$^{-3}$ Ohms of cm is received at the density of energy of 4,6 J $\cdot$ cm$^{-2}$, temperature of a substrate 300$^\circ$С both oxygen 20 pressure мТорр and concentration of antimony in a film 2 ат. %. The average coefficient of a transmission in visible area of a range of such films made 85%, and the optical band gap is 5,3 eV. The roughness of films didn't exceed 30 nanometers.
Discussion of results: Thin films of SnO$_2$:Sb by method of pulse laser deposition in the droplet-free regime on substrates from quartz glass without the subsequent annealing are received. Structural, electric and optical properties of the films received under various conditions of deposition are investigated. It is established that energy density on targets and level of an alloying of films of SnO$_2$ antimony influence their transmission and conductivity. Optimum conditions of receiving films by the PLD the droplet-free method from the point of view of high transparency in visible area of the spectrum and good conductivity are determined. Influence of level of an alloying on characteristics of films (conductivity, transparency, phase structure and morphology of films) is established. Optimum conditions of receiving films of SnO$_2$:Sb from the point of view of high conductivity and transparency in visible area of the spectrum at the lowest temperature of a substrate that is very important for the deposition of such films on flexible organic substrates are defined.
Practical importance: Use of a method of the pulse laser deposition providing increase in energy of particles in a plasma plume at synthesis of thin films will allow to apply these materials on flexible polymeric organic substrates thanks to essential decrease in temperature of crystallization of films. New material for transparent electrodes and p-n-transitions on their basis which is necessary for development of optoelectronic devices is received and investigated.