Global Journal of Researches in Engineering, G: Industrial Engineering, Volume 23 Issue 2

Photosensitive Structure with Schottky Barrier based on Nickel-Silicon Silicon Contact Abstract- Measured resistivities of produced silicide showed their good c onductive properties. The calculation of technological route for obtaining thin silicide contacts (<100A 0 ) in multilayer metallization of Si substrate was carried out, and the optimal technological regimes for obtaining Pd, Pt and Ni silicide in single-layer metallization of Si substrate were determined. Keywords: resonant-frequency method, optical constants, multibeam interferometry method, quartz element. I. I ntroduction n a metal-semiconductor contact, depending on the ratio between the values of the electron yield work in the metal ψ m and in the semiconductor χ +V n , electrons as a result of internal emission may pass from metal to semiconductor or vice versa. In this case, a part of electrons from the metal (silicide) goes to the semiconductor (Si) until thermodynamic equilibrium occurs and the Fermi levels in the metal and in the semiconductor are equalized [1,2]. In the vicinity of the semiconductor-metal interface in the semiconductor an area of depleted charge carriers arises, an area of bulk charge of uncompensated negative acceptor ions whose electric field prevents the further emission of electrons from metal to semiconductor, the semiconductor energy bands bend downwards. If the thickness of the intermediate layer is atomic distance, then the magnitude of the curvature of the height of the potential barrier equals the contact potential difference = Ф − Ф + � − � = + − Ф , Under the influence of IR radiation two types of electronic transitions can take place in such a structure. If the incident photon energy h ν ≥ E g , then electron-hole pair generation occurs when it is absorbed in the semiconductor. In this case, as well as in an ordinary photodiode on a p-n junction, carriers of different sign on the junction field separate and photo-electric power arises. It is obvious that the long-wave limit of such a process cannot be less than the band gap width of the semiconductor, and from this point of view the Schottky barrier photodiodes do not differ from p-n photodiodes or their own photoresistors. If h ν <E g then infrared absorption in a metal film excites valence electrons to states above the Fermi level, leading to holes, some of which have energy greater than the barrier height Ψ ms . Then either the hole is emitted from the metal to the semiconductor, or the electron moves from the semiconductor to the metal, filling the empty state [3,4]. To overcome the metal-to-semiconductor barrier, the energy of the excited hole must be greater than the height of the barrier. The long-wave boundary of such a process can be changed by selecting the appropriate metal. Therefore, from the point of view of creating silicon-based IR photodetectors the greatest interest is the photoemission from metal to semiconductor. a) Experiment In the first step, the 0,5 µm thick SiO 2 oxide layer was grown on p-type (100) silicon wafers (KDB- 10). Before this operation the silicon wafers were degreased with trichloroethane, acetone and alcohol and cleaned in a CCl 4 boiling solution. Before metal (Ni) sputtering, windows of 2·2 mm and 4·4 mm were opened in the SiO 2 film using photolithography techniques. Metal sputtering was carried out thermally in a vacuum of 10 -5 mmHg. The substrate temperature was maintained at 200 0 C. Immediately before loading into the vacuum chamber Si wafers were pickled by buffer solution of HF (34,6%NH 4 F + 6,8%HF + 58,6%H 2 O) with the following washing of wafers in deionized water and drying in isopropyl alcohol vapor. After metal deposition the silicon wafers were annealed at T ann = 510 0 C and T ann = 900 0 C for t = 30 min in N 2 atmosphere to obtain NiSi - Si and NiSi 2 - Si structures. Fig. 1 shows the cross-section of the investigated structures. Photoconductivity spectra of the obtained NiSi - Si and NiSi 2 - Si structures with the Schottky barrier were studied. I Author: Azerbaijan Technical University H. Javid pr. 35, AZ 1073, Baku, Azerbaijan. e-mail: E_Kerimov.fizik@mail.ru © 2023 Global Journals Global Journal of Researches in Engineering Volume XxXIII Issue II Version I 21 Year 2023 ( ) G where, the second term is the difference between the yield work of the metal and the electron affinity of the semiconductor. E. A. Kerimov