Performance of gas source MBE-grown wavelength-extended InGaAs photodetectors with different buffer structures

• Published in: Journal of crystal growth 2009-03, Vol.311 (7), p.1881-1884
• Main Authors: Zhang, Y.G., Gu, Y., Tian, Z.B., Wang, K., Li, A.Z., Zhu, X.R., Zheng, Y.L.
• Format: Article
• Language: English
• Subjects: A3. Molecular beam epitaxy; Applied sciences; B2. Semiconducting III–V materials; B3. Infrared devices; Cross-disciplinary physics: materials science; rheology; Electronics; Exact sciences and technology; Materials science; Methods of crystal growth; physics of crystal growth; Methods of deposition of films and coatings; film growth and epitaxy; Molecular, atomic, ion, and chemical beam epitaxy; Optoelectronic devices; Physics; Semiconductor electronics. Microelectronics. Optoelectronics. Solid state devices; Theory and models of crystal growth; physics of crystal growth, crystal morphology and orientation
• ISSN: 0022-0248; 1873-5002
• DOI: 10.1016/j.jcrysgro.2008.10.087

Wavelength-extended In y Ga 1− y As photodiodes with cut-off wavelengths of 2.0, 2.4 and 2.7 μm at room temperature were grown using gas source molecular beam epitaxy with linearly graded In x Al 1− x As ( x=0.52 to y) buffer layers and In y Al 1− y As cap layers. A convenient and reliable correlating ramping procedure was developed for the growth. Detector performances were compared with our standard homojunction detectors containing linearly graded In x Ga 1− x As buffer layers. The heterojunction detectors showed better performance than the homojunction detectors. Also, the use of wider bandgap buffer and cap made the heterojunction detectors more suitable for both front and back illumination. For the photodiodes with 500 μm mesa diameter at room temperature, the typical dark current ( V R=10 mV) and R 0 A were 74 nA and 104 Ω cm 2 at 290 K for the cut-off wavelength of 2.4 μm. Optimization of the buffer structure was necessary for further extension of the response wavelength.