tailieunhanh - Electronic Materials Part 7

Tham khảo tài liệu 'electronic materials part 7', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | Quantum Wells L If we approximate well as having infinite potential boundaries k ỴỊL for standing waves in the potential well h 2k 2 h2n2 We can modify electronic E 2m 8m L2 transitions through quantum wells E. Fitzgerald-1999 Artificially Modulated Structures . Tuller 2001 7 Photodetectors Solar Cells E-h pairs generated by photons with energy hỵ Eg are separated by the built-in potential gradient at the p-n junction. The current voltage characteristics are given by I Io exp qV kT -1 - Ip where Ip is the photo-induced reverse current. Junctions Functions Junction Function Application P n Metal semiconductor Injection diffusion collection Blocking reverse bias p-n rectifier switch p-n-p transistor Acceleration breakdown Tunneling Avalanche and tunnel diodes Injection confinement recombination LED injection laser Generation separation Solar cell photodiode Separation confinement High electron mobiity devices Quantum devices M I S Inversion depletion accumulation MOSFET . Tuller 2001 8 The Capacitor The air-gap can store energy If we can move charge temporarily without current flow can store even more Bound charge around ion cores in a material can lead to dielectric properties Two kinds of charge can create plate charge surface charge dipole polarization in the volume Gauss law can not tell the difference only depends on charge per unit area E. Fitzgerald-1999 2