半导体英文课件 PN and Metal-Semiconductor Junctions.ppt

Modern Semiconductor Devices for Integrated Circuits (C. Hu) Slide 4-* 4.13.1 LED Materials and Structure 　  red yellow blue 　 Wavelength (μm) Color Lattice constant (?) InAs 0.36 3.44 　 6.05 InN 0.65 1.91 infrared　 3.45 InP 1.36 0.92 violet 5.87 GaAs 1.42 0.87 5.66 GaP 2.26 0.55 5.46 AlP 3.39 0.51 5.45 GaN 2.45 0.37 3.19 AlN 6.20 0.20 UV 3.11 Light-emitting diode materials compound semiconductors binary semiconductors: - Ex: GaAs, efficient emitter ternary semiconductor : - Ex: GaAs1-xPx , tunable Eg (to vary the color) quaternary semiconductors: - Ex: AlInGaP , tunable Eg and lattice constant (for growing high quality epitaxial films on inexpensive substrates) Eg(eV) Red Yellow Green Blue Modern Semiconductor Devices for Integrated Circuits (C. Hu) Slide 4-* Common LEDs Spectral range Material System Substrate Example Applications Infrared InGaAsP InP Optical communication Infrared-Red GaAsP GaAs Indicator lamps. Remote control Red-Yellow AlInGaP GaA or GaP Optical communication. High-brightness traffic signal lights Green-Blue InGaN GaN or sapphire High brightness signal lights. Video billboards Blue-UV AlInGaN GaN or sapphire Solid-state lighting Red-Blue Organic semicon-ductors glass Displays AlInGaP Quantun Well Modern Semiconductor Devices for Integrated Circuits (C. Hu) Slide 4-* 4.13.2 Solid-State Lighting Incandescent lamp Compact fluorescent lamp Tube fluorescent lamp White LED Theoretical limit at peak of eye sensitivity ( λ=555nm) Theoretical limit (white light) 17 60 50-100 90-? 683 ~340 luminosity (lumen, lm): a measure of visible light energy normalized to the sensitivity of the human eye at different wavelengths Luminous efficacy of lamps in lumen/watt Terms: luminosity measured in lumens. luminous efficacy, Organic Light Emitting Diodes (OLED) : has lower efficacy than nitride or aluminide based compound semiconductor LEDs. Modern Semiconductor Devices for Integrated Circuits (C. Hu) Slide 4-* 4.14 Diode Lasers (