Facile deposition of GaAs thin film on glass substrate via post annealing in open air

Introduction Since in 1920 Goldschmidt has been discovered Gallium Arsenide and later confirmed it in 1929 [1]. GaAs is a compound semiconductor. Gallium has extracted from various materials such as zinc ores and bauxite and more valuable than gold. Arsenic is toxic, but ordinary material. GaAs has a crystal shape known sphalerite (zinc blende) lattice Practical applications of Gallium Arsenide are photovoltaic, high brightness LEDs and, ultimately, all optical space switch technologies [4]. The bandgap of GaAs is 1.42eV which is closer to the standard band gap energy of 1.5eV for solar energy conversion [5]. It is broadly used in the semiconductor fabrication due to its extensive direct band gap energy and higher electron mobility than Si [6]. GaAs has high radiation tolerance and efficiency as compared to other solar cells. Due to this reason in 1980s Radio Corporation of America and USA States Department of Defense first used GaAs as a microprocessor for Star Wars programs [6]. It is used in various applications such as beam combiners, beam splitters, and polarizer as substrates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he amorphous and crystalline thin film of GaAs on different substrates has been formed with various methods, such as electron beam evaporation, sputtering, molecular beam epitaxy(MBE) and pulsed laser deposition (PLD) [9]. Diverse applications of GaAs are well fitted with advanced future technology such that electronics, optoelectronics, and thin film applications. In this research work, GaAs samples were prepared by a resistive heating evaporation technique. Furthermore, we have explored first time the effect of annealing in an open air of GaAs films and also characterized the same samples with help of RBS and EDS to find out the comparative effect of elemental compositions. We have also verified in details all samples with help of XRD, SEM, EDS, and RBS. Crystallinities of post-annealed films were evaluated by XRD. X-ray diffractometer (JEOL JDX3532), using CuKα energy emissions . Surface morphologies and structures of films were carried out by Scanning Electron Microscope (JEOL JSM5910). The samples composition carried out by EDX. The samples thickness and sample elemental composition analysis also were determined by Rutherford Backscattering Spectrometry (RBS) technique. RBS experimental details as following, accelerator (5MV Pelletron Tandem Accelerator), beam (He++), energy (2.084 MeV), detector (Solid State Barrier (SSB)), resolution of detector (20 KeV), backscattering angle (170o), incident angle (0o), charge (15 uC), current (26 nA), Software (RC43, XRUMP, SIMNRA). Experimental details First of all, keep the glass substrates in acetone and then in deionized water into an ultrasonic vessel for 20 minutes each to remove contaminations. Clean substrates keep in a suitable environment at room temperature before using for evaporation. In this experiment resistive heating evaporation unit “EdwardE306A, UK” was used shown in figure 1. Glass slides used as substrates; multi substrates kept inside the substrate rotor. The GaAs powder purity (99.999%, Beijing Goodwill Metal Technology Co. Ltd) keeps in tantalum (Ta) foil boat. The distance between substrates rotor and boat has round about 5cm and rotor located opposite to the boat. GaAs thin film on glass substrates was grown under a vacuum pressure 7.6×10-5 mbar at room temperature and deposition time has count just 6 minutes. After that, we have selected three most suitable samples for further characterizations. Furthermore, keep the samples one by one in homemade tube furnace (maximum range 1400℃) in an open air each for 20 minutes annealing. The reading of annealing temperatures was 250oC for sample 250, 280oC for sample 280 and 320oC for sample 320