Metamorphic InGaAs p-i-n Photodetectors with 1.75 μm Cut-Off Wavelength Grown on GaAs

• Published in: Chinese physics letters 2010-03, Vol.27 (3), p.324-327
• Main Author: 朱彬 韩勤 杨晓红 倪海桥 贺继方 牛智川 王欣 王秀平 王杰
• Format: Article
• Language: English
• Subjects: InGaAs; 分子束外延生长; 室温探测器; 截止波长; 砷化铟镓; 砷化镓衬底
• ISSN: 0256-307X; 1741-3540
• DOI: 10.1088/0256-307X/27/3/038504

Top-illuminated metamorphic InGaAs p-i-n photodetectors （PDs） with 50% cut-off wavelength of 1.75 μm at room temperature are fabricated on GaAs substrates. The PDs are grown by a solid-source molecular beam epitaxy system. The large lattice mismatch strain is accommodated by growth of a linearly graded buffer layer to create a high quality virtual InP substrate indium content in the metamorphic buffer layer linearly changes from 2% to 60%. The dark current densities are typically 5 × 10^-6 A/cm^2 at 0 V bias and 2.24 × 10^-4 A/cm^2 at a reverse bias of 5 V. At a wavelength of 1.55 μm, the PDs have an optical responsivity of 0.48 A/W, a linear photoresponse up to 5 mW optical power at -4 V bias. The measured -3 dB bandwidth of a 32 μm diameter device is 7 GHz. This work proves that InGaAs buffer layers grown by solid source MBE are promising candidates for GaAs-based long wavelength devices.