In the past, infrared imaging has been used exclusively for military applications. In fact, it can also be useful in a wide range of scientific and commercial applications. However, its wide spread use was impeded by the scarcity of the imaging systems and its high cost. Recently, there is an emerging infrared technology based on quantum well intersubband transition in III-V compound semiconductors. With the new technology, these impedances can be eliminated and a new era of infrared imaging is in sight. This book is designed to give a systematic description on the underlying physics of the new detectors and other issues related to infrared imaging.
Part 1 Fundamentals: blackbody radiation and flux transfer; blackbody radiation; flux transfer; signal and noise in photoconductors; optical signal of a photoconductor; noise in a photoconductor. Part 2 Energy levels in one-dimensional quantum wells: analytical method; Wentzel-Kramers-Brillouin approximation; Kronig-Penney model; transfer-matrix method. Part 3 Quantum wells in crystal lattices: finite in-plane momentum; crystal symmetries and band structures of GaAs; basic properties of a group; symmetry group of a GaAs crystal lattice; k.p perturbation theory; band nonparabolicity. Part 4 Quantum wells in the presence of interaction: direct Coulomb interaction; electron-electron interaction; electron-phonon interaction; static electric field; oscillating electric field. Part 5 Intersubband transitions in quantum wells: theory of dipole transitions; bound-to-bound intersubband transitions; square quantum wells; stepped quantum wells; strongly-coupled quantum well; bound-to-extended intersubband transitions; bound-to-miniband transitions; decoupled quantum wells; coupled quantum wells. Part 6 Optical coupling for normal incidence: square gratings; random gratings; corrugated QWIP structures; quantum grid infrared photodetectors. Part 7 Hot-electron transistors: phase coherence of ballistic electrons; plasmon and phonon emission by hot-electrons; magnetophonon scattering. Part 8 Excitation hot-electron spectroscopy of quantum wells: thermal excitation; optical excitation. Part 9 Transport properties of multiple quantum well structures: perturbation approach to tunnelling; sequential tunnelling; thermionic emission; thermally assisted tunnelling; tunnelling in the presence of a magnetic field. Part 10 Quantum well infrared photodetectors: photoconductivity of multiple quantum wells; responsivity of thin barrier MQWs; electron-electron inelastic scattering in MQWs; avalanche multiplication in MQWs; responsivity of thick barrier MQWs; capture probability; quantum noise characteristics of QWIPs; optimization of QWIPs. Part 11 Infrared hot-electron transistors: detector figures of merit; readout circuits and dark current requirements; infrared hot-electron transistors; high detectively IHETs; IHETs for small NEAT; IHETs for high temperature operation; long wavelength IHET; signal amplification and quasi-photovoltaic operation of IHETs. Part 12 Noise in infrared hot-electron transistors: quantum partition noise; l/f noise. Part 13 Multi-colour infrared detection: strongly-coupled asymmetric quantum wells; photoexcited coherent tunnelling; voltage tunable multi-colour QWIPs; voltage tunable multi-colour IHETs. Part 13 Performance assessment of quantum well infrared photodetectors: an assessment of the conventional technologies; an assessment of the quantum well technology. Part 14 QWIPs and IHETs in focal plane array applications: examples for QWIPs; examples for IHETs.