Haji-Sheikh, Michael J.||Rajashankar, Suma
M.S. (Master of Science)
Department of Electrical Engineering
The characterization of Schottky diodes created on the surface of porous silicon substrates is an important step in creating commercially viable devices. The applications of Schottky diodes are numerous. These diodes can be used as solar cells, power rectifiers, switches, and gas detectors etc. Using a Schottky diode as a switch has many benefits because of its faster switching speeds. The conventional Schottky diodes used the normal bulk n-type (or p-type) substrate to build the diode and to use a metal to form a junction called the Schottky junction. When we change the substrate to porous silicon, in place of bulk silicon, we can take advantage of the shift in band gap and the capillary effect caused by the pores. Porous silicon is prepared using specific etching techniques. Silicon nitride is coated both on the front and back side of the wafers and using dry etching silicon nitride on the back is etched off. The front side is etched using positive photoresist patterning. The wafer is diced using a wafer saw and dipped in an etching solution to perform etching. Because of the Si3N4 hard mask, localized pores are formed during etching in the area free of the hard mask. After etching, the pores can be observed using Scanning Electron Microscopy. When the formation of pores is confirmed the etched samples are metallized using chromium and gold, titanium and gold, tungsten and gold. The device is then tested for Schottky diode characteristics using probe station. The ability to sense light and gases is also tested. The resulting I-V graphs are then viewed using the device monitor in MRDL and analyzed.
Selvam, Karthik, "Comparison of barrier heights of selected refractory metals on porous p-type silicon" (2018). Graduate Research Theses & Dissertations. 1860.
Northern Illinois University
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Advisors: Michael J. Haji-Sheikh; Suma Rajashankar.||Committee members: Mansour Tahernezhadi; Donald Zinger.||Includes illustrations.||Includes bibliographical references.