1 MORPHOLOGICAL AND OPTICAL PROPERTIES OF THERMAL EVAPORATION ALUMINUM DOPED TIN (ΙΙ) SULFIDE THIN FILM FAIZ HASHIM 1,a* , WAN NURULHUDA WAN SHAMSURI 1,b , RASHID AHMED 1,c and KARIM DERAMAN 1,d . 1 Faculty of Science, Universiti Teknologi Malaysia, 81310 UTM Skudai, Johor, Malaysia a faizhashim232@gmail.com, b wnurulhuda@utm.my, c rashidahmed@utm.my, d karimd@utm.my. Keywords: Tin Sulfide, Thin film, Thermal evaporator, Atomic force microscope, Semiconductor. Abstract. Having near optimum energy band gap (In the range of 1.3-1.4 eV) and higher absorption coefficient (α > 10 4 cm -1 ) make tin sulfide a promising semiconductor material for photovoltaic usage. Tin sulfide has also been considered as alternative material for solar cell due to its non-toxicity and abundant in nature compared to indium and cadmium based solar cell. For this research, aluminum dopant had been introduced to tin sulfide thin films to alter its properties. Aluminum doped tin sulfide thin films were deposited using thermal evaporator onto a glass substrate and annealed in a vacuum environment for 2 hours. The effects of annealing process towards the morphologies of aluminum doped tin sulfide thin films were analyzed. The morphological properties of the sample were evaluated using Atomic Force Microscope (AFM). The thickness and roughness of the sample surface were investigated for determining the growth mechanism of the aluminum doped tin sulfide thin films. Introduction Recently many researchers are trying to find a cost-effective absorber material for solar cell application. It involves materials that are low-cost, environmental friendly, abundant in nature and high energy conversion efficiencies [1]. It has been proven recently that tin sulfide is one of the suitable candidate to replace cadmium and indium based solar cell [2]. Tin sulfide is the new potential absorber layer for solar cell, due to its high absorption coefficient (α > 10 4 cm -1 ) [3] and near optimum energy bandgap (1.4eV)[1], [4]. Dopant material such as antimony (Sb) [5], silver (Ag) [6] and bismuth (Bi) [7] was introduced to tin sulfide thin film sample for producing a higher efficient solar cell. Doping process was carried out to alter the structural, optical and electrical properties of tin sulfide thin film samples. Based on previous research, it is founded that doping process may have affected the electrical resistivity of tin sulfide thin film due to the change amount of carrier concentration [8]. For this research aluminum (Al) were utilized as doping agent. Thermal evaporation method was used to fabricate all the aluminum doped tin sulfide thin films. Then, all samples were undergoes annealing process for 2hours in a vacuum environment. The main objective for the study is to investigate the effect of annealing process toward the morphological properties and the optical bandgap of aluminum doped tin sulfide thin film samples. Atomic force microscope (AFM) and UV-Vis spectrophotometer were used to carry out the study. Methodology