Impact of deposition temperature on crystalline quality, oxygen vacancy, defect modulations and hetero-interfacial properties of RF sputtered deposited Ga₂O₃ thin films on Si substrate

Abstract

In the current work, thin film (~55 nm) of n-type Ga2O3 (n-Ga2O3) is deposited on silicon (p-Si) substrate by using Radio-frequency (RF) sputtering technique with systematic substrate temperature variations (room temperature (RT) to 700 oC). The structural, optical properties and chemical states of elements of the deposited films are observed to depend significantly on the deposition temperatures. The chemical composition and oxidation states, optical properties, defect states and structural quality of the deposited films are investigated in detail by employing XPS, EDX, SE, Raman, PL and AFM images. XRD result reveals a polycrystalline nature of monoclinic β-phase of Ga2O3 with (403) dominant plane. The work functions are calculated from the UPS for all the deposited films and Ga2O3/Si heterojunction properties are investigated by using Current-Voltage (I-V) and Capacitance-Voltage (C-V) measurements. Among all the fabricated heterojunctions, 600 oC deposited Ga2O3 film exhibits superior performance in terms of energy bandgap, work function, refractive index, barrier height, rectification ratio and effective carrier concentrations. The current transport mechanism is analysed using the appropriate energy band diagram of Ga2O3 and Si. Therefore, the study suggests that 600 oC deposition temperatures is the optimum temperature for developing a high quality Ga2O3 thin film on Si by using RF sputtering technique and corresponding Ga2O3 thin film/Si heterojunction can be a potential candidate for developing several electronic and optoelectronic devices.

Tunable Ga2O3 solar-blind photosensing performance via thermal reorder engineering and energy-band modulation

“…Figures 1(a)-(d) shows the surface and cross-sectional morphologies of the four Ga 2 O 3 films photographed by FE-SEM. The surface of the film annealed in vacuum is rougher than the other three samples, which may be attributed to a co-effect of high-temperature reorganization and recrystallization of the crystal surface in the oxygen-deficient condition [24][25][26]. The thicknesses of the films after annealing increased significantly, and the two samples annealed in oxygen atmosphere are even thicker; in a rich oxygen atmosphere, the Ga 2 O 3 films will grow further in addition to recrystallizing [19].…”

Improvements in Resistive and Capacitive Switching Behaviors in Ga2O3 Memristors via High-Temperature Annealing Process

“…The Ga-O, located at a binding energy of 530.0 eV, corresponded to the O 2− ions surrounded by Ga atoms. Conversely, the Vo peak, positioned at a binding energy of 531.6 eV, was attributed to the presence of oxygen vacancies [ 35 ]. Upon thermal treatment at 800 °C, the ratio of Vo peak area (Vo/[Ga-O + Vo]) to the total area of the O1s peak increased from 23% to 28% for the as-grown Ga 2 O 3 thin film.…”

Influence of Nitrogen Annealing Treatment on Optical, Microstructural, and Chemical Properties of Ga2O3 Film Grown by Plasma-Enhanced Atomic Layer Deposition

“…Typically, β-Ga 2 O 3 thin films prepared by ALD exhibit dislocation defects and oxygen vacancies, which greatly affect the crystal quality as well as the optical and electrical properties of the thin films. − High-temperature annealing can effectively release the stress between the film and substrate and eliminate dislocation defects. High-temperature annealing provides enough energy for gallium and oxygen atoms to move to the appropriate lattice position, which is conducive to the selective growth of the film .…”