Yong-Gang Zhang

By Yong-gang Zhang and Yi Gu

Part of the book: Advances in Photodiodes

By Yong-gang Zhang and Yi Gu

Part of the book: Photodiodes

By Yi Gu and Yong-Gang Zhang

Mid-infrared semiconductor lasers in the wavelength range of 2-3 µm have aroused increasing interests as they are highly desired for a wide range of applications ranging from medical diagnostics to environmental sensing. Access to this wavelength range was mainly achieved by antimony-containing compound semiconductor structures on GaSb substrates. Besides, InP-based InxGa1-xAs (x>0.53) type-I multiple quantum well laser is a promising antimony-free approach in this band. The emission wavelength can be tailored to the 2-3 µm band by increasing the indium composition in the quantum wells. During the demonstration of this kind of lasers, controlling the strain and keeping fair structural quality is the main obstacle.

Part of the book: Optoelectronics

By Xing-you Chen, Yi Gu and Yong-gang Zhang

In this chapter, our works on the developments of wavelength-extended InGaAs photodetectors with cutoff wavelength >1.7 μm are reviewed. Various InGaAs/InAlAs p-i-n heterojunction structures have been grown on InP and GaAs substrates by gas source molecular beam epitaxy, some details on the InGaAs photodetector structures and the techniques of metamorphic buffer layer such as linearly, step, and one-step continuously InAlAs graded buffer, and dislocation restraint methods of compositional overshoot and digital alloy are introduced. The material characteristics and device properties were evaluated by atomic force microscopy, high-resolution X-ray diffraction and reciprocal space mapping, cross-sectional transmission electron microscopy, and current-voltage measurements, etc. The results provide clues to the development of metamorphic device structures on lattice-mismatched material systems.

Part of the book: Epitaxy