unsw新南威尔士大学课件《应用光伏》第四讲：半导体-载流子产生和负荷,pn结 sola2540-9001_lecture 4.pdf

SOLA2540 9001 Applied Photovoltaics Semester 2, 2013 School of Photovoltaic and Renewable Energy Engineering Carrier generation recombination Carrier transport p-n junctions Dr Santosh Shrestha s.shrestha@unsw.edu.au Learning Objectives • Explain absorption, carrier generation and recombination in semiconductors. • Describe drift and diffusion currents in semiconductors. • Describe p-n junction in equilibrium, forward bias and reverse bias. • Explain how photo-generated carriers are separated by a p-n junction . • Define “Depletion Region”, “Build in potential”, and “depletion widths”. • Describe ideal and actual diode equations for a p-n junction . SOLA2540-9001 S2 2013 Dr Santosh Shrestha 2 s i Absorption of Light (1): Photogeneration n t o n r e t l c a e v l o e c e Ec Conduction photon energy is a h t n Band stored in the i d n n separation of the o a r , E e-h pair across t ” g c e the bandgap e l l o . e h n n “ E o a a v Valence i t y g . Band p b n d r i +