Abstract— The energy band diagram and space charge regions of Schottky barrier (SB) solar cells are different from normal pn solar cells. Many facts and theories must be studied and developed to assist understanding and implementing SB solar cells. Few samples of SB devices were prepared by thermal deposition under vacuum then tested and studied carefully. An interfacial layer was introduced between metal and semiconductor. I-V and C–V are measured, drawn and discussed in details. The current transportation mechanism of the prepared samples is found to be of thermal mechanism type. The current transportation depends on the potential barrier height. From C– V characteristics, it is found that the potential barrier height is decreased as the interfacial oxide becomes thicker. Index Terms— MOS structures, MOS Solar cells, Schottky barrier diode. I. INTRODUCTION chottky barrier (S B) diodes have many electronic properties; some of them are shared with normal PN junction, such as structure and potential barrier. Others are different such as energy band diagram and space charge region that formed at semiconductor side. In addition, potential barrier height is usually less than energy gap of semiconductor, and current transportation mechanism of SB is due to thermal emission. For all these reasons many facts and theories have been developed and implemented to assist understanding Schottky barrier behaviors [1, 2, 3] and to use them as a solar cell [4,5] or as a photo detector [6,7]. Schottky barrier used to detect the ultraviolet, visible and infrared rays. The structure of S B make it suitable for short wavelength detection, this is Manuscript received October 13, 2010. This work was supported in part by Philadelphia university, Amman, Jordan 1-Dr. WAGAH F. MOHAMAD, Communications & Electronics Department, Faculty of Engineering, Philadelphia University, Amman, Jordan. Email: wagahfaljubori@yahoo.com 2-Eng. Nada Nabil Khatib, Communications & Electronics Department, Faculty of Engineering, Philadelphia University, Amman, Jordan. Email: nadakhtb@yahoo.com 3- Dr. Ayed N. Saleh, Physics Department, College of Science, Tikrit University, Tikrit, IRAQ, Email: ayednsaleh@yahoo.com due to current transportation carried out by the majority carriers and not to generation- recombination process as in normal PN junctions. Another advantage of S B is that it is easy to fabricate with low break down voltage and high leakage current [8]. II. METAL INDUCED GAP STATES (MIGS) IN METAL- SEMICONDUCTOR CONTACT The generated gap states were found in all Schottky barrier diodes. They are moved from the donor level near the top of valance band to the accepter level underneath the conduction band. It is evident now that an interfacial layer formed between metal and semiconductor. This model proposed that the formation of such gap states is due to chemical defects (oxide layer) or the dangling bonds. If the oxide is very thin the electrical properties of the junction are the same as normal or Schottky barrier in which the electron can tunnel through the thin oxide layer. The potential barrier height in MIS structured depends very strongly on the type and thickness of the oxide layer. It is proved that the barrier height is inversely proportional with oxide thickness [9]. Fig. 1 represents the current transportation mechanism [10]. From semiconductor type (n) to metal in metal-semiconductor (n) junction they can be represented by four types: (a) Thermal electron emission (b) Tunneling through potential barrier, (c) recombination at space charge region and (d) recombination at the neutral zone (carrier injection) [10]. Type (a) current transportation is the most important mechanism, and current density (J Sat ) due to this mechanism is given by: Some Aspects of Electronic Properties of Schottky Barrier Photo detector Dr. WAGAH F. MOHAMAD, Eng. Nada Nabil Khatib, Dr. Ayed N. Saleh S c d V d ε a b φ b Fig. 1: Represents current transportation from semiconductor to metal at forward bias. 2011 8th International Multi-Conference on Systems, Signals & Devices 978-1-4577-0411-6/11/$26.00 ©2011 IEEE