CHAPTER OBJECTIVES This chapter introduces several devices that are formed by joining two different materials together. PN junction and metal-semiconductor junction are analyzed in the forward-bias and reverse-bias conditions. Of particular importance are the concepts of the depletion region and minority carrier injection. Solar cells and light-emitting diode are presented in some detail because of their rising importance for renewable energy generation and for energy conservation through solid-state lighting, respectively. The metal-semiconductor junction can be a rectifying junction or an ohmic contact. The latter is of growing importance to the design of high-performance transistors. PART I: PN JUNCTION As illustrated in Fig. 4-1, a PN junction can be fabricated by implanting or diffusing (see Section 3.5) donors into a P-type substrate such that a layer of semiconductor is converted into N type. Converting a layer of an N-type semiconductor into P type with acceptors would also create a PN junction. A PN junction has rectifying current-voltage (I-V or IV) characteristics as shown in Fig. 4-2. As a device, it is called a rectifier or a diode. The PN junction is the basic structure of solar cell, light-emitting diode, and diode laser, and is present in all types of transistors. In addition, PN junction is a vehicle for studying the theory FIGURE 4-1 A PN junction can be fabricated by converting a layer of P-type semiconductor into N-type with donor implantation or diffusion.
CITATION STYLE
Razeghi, M. (2019). Semiconductor p-n and Metal-Semiconductor Junctions. In Fundamentals of Solid State Engineering (pp. 319–363). Springer International Publishing. https://doi.org/10.1007/978-3-319-75708-7_9
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