21. Electron wave functions are repeated in each period of a three quantum well QCL active region. 22. This allows for extremely high performance high electron mobility, HEMT transistors, and other quantum well devices. 23. Quantum well infrared photodetectors are also based on quantum wells , and are used for infrared imaging. 24. Two closely spaced heterojunction interfaces may be used to confine electrons to a rectangular quantum well . 25. Where N is the number of quantum wells . 26. In 1998, Viaspace signed a memorandum of understanding with RGC to commercialize a Quantum well infrared photodetector. 27. He elaborated a theory of electron transport phenomena in quantum wells , classical and size-quantized films, and superlattices. 28. Briefly, as an electron hops from one quantum well to another neighbouring well it produces a phonon. 29. Lasers containing more than one quantum well layer are known as " multiple quantum well " lasers. 30. Extensive work has been performed on quantum well lasers based on gallium arsenide and indium phosphide wafers.
