InP/GaAs, GaAs/Si And InP/GaAs/Si Heteroepitaxy Technologies And Their Applications In Integrated Optoelectronic Devices

The increasing demand for communication is driving force behind modern fiber communication systems, which are always based on novel optoelectronic devices. It is revolutionary period that independent devices change to optoelectronic integrated devices, which have been encountered by the compatibilities of semiconductor materials, structures and processes.The research work of this doctoral thesis is mainly supported by the grants from the National Basic Research Program of China (No.2003CB314900), which professor Xiaomin Ren is responsible for as a chief scientist, the National High Technology Research and Development Program of China(No: 2003AA31g050, 2006AA03Z416, 2007AA03Z418), Key Program of the National Natural Science Foundation of China(No. 90601002, 60576018) and Program of Key International Science and Technology Cooperation Projects (2006DFB11110). In this thesis, a great deal of work is demonstrated about theorical and experimental research on heteroepitaxy of large mismatched materials, including InP/GaAs, GaAs/Si and InP/GaAs/Si. Based on high quality hoteroepitaxy, the novel monolithically integrated GaAs-based and Si-based wavelength-selective photodetectors has been successfully fabricated first time. The main achievements are listed as follows:1. Important progress has been achieved on InP/GaAs heteroepitaxy. The optimum conditions of low temperature InP buffer layer and the optimum structures of InP/Ga_0.1In_0.9P strained layer superlattice (SLS) have been obtained. Based on these methods, a 2.6μm high quality InP epilayer has been grown on GaAs substrates by using low pressure metalorganic chemical vapor deposition (LP-MOCVD). The FWHM of X-ray diffraction (XRD)ω-2θscans is only 208arcsec. Test results indicate the dislocation density of InP epilayer has been reduced to 10⁷cm^-2.2. The monolithically integrated long-wavelength tunable "One-Mirror Inclined Three-Mirror Cavity" photodetector has been realized first time. By employing a thin low-temperature buffer layer, the high quality InP-based p-i-n structures and taper-fabricated layers have been grown on a GaAs-based GaAs/AlAs Fabry-Pérot-filter. A wavelength tuning range of 10.0 nm, an external quantum efficiency of about 51.5%, a spectral linewidth of 0.8 nm and a 3-dB bandwidth of 6.0 GHz have been obtained in this device.3. Detailed analysis and fabrication of a monolithically integrated dual-wavelength tunable photodetectors has been demonstrated. The dual-wavelength character is realized first by fabricating a taper GaAs substrate with the angle of 3°. The photodetector is monolithically integrated by using a heteroepitaxy growth of InP-In0.53Ga0.47As-InP p-i-n structure on a GaAs-based GaAs/AlAs Fabry-Perot-filter structure, which can be tuned via the thermal-optic effect. High-quality heteroepitaxy was realized by employing a thin low-temperature buffer layer. The devices with a dual-peak distance of 7 nm (1530nm, 1537 nm), a wavelength-tuning range above 5.0 nm, and a 3-dB bandwidth of 6.4 GHz are successfully fabricated. The potential applications have been discussed also.4. Important progress has been achieved on GaAs/Si heteroepitaxy. High-quality GaAs epilayer is obtained by employing the technologies of the tilted Si substrate, optimization the low temperature Al(GaAs)As buffer layer and thermal cycle annealing. The FWHM of XRDω-2θ scans is only 192.3arcsec for a 1.2μm GaAs material grown on Si substrates. Transmission Electron Microscope (TEM) shows the density of threading dislocation in epilayers has been bended and joined. These results indicate the dislocation density has been reduced to 10⁷cm^-2 in the epilayer of 0.5μm away from the interface of GaAs/Si.5. A method of GaAs epilayer grown on mid-patterned Si subatrates has been demonstrated. The large area (700μm×800μm) crack-free GaAs/Si mesas with the thickness of 13μm have been realized, which are regrown on the patterned Si substrates covered by the pregrown 1-3μm GaAs layer. The crack-free characteristic is introduced by the release of thermal stress in the epilayers.6. The epilayers including 13μm GaAs-based GaAs/AlAs Fabry-Perot-filter and 5μm InP based p-i-n structure have been grown on Si substrates by employing the methods of mid-patterned Si substrate and the InP/GaAs low temperature buffer. Then the epilayers are fabricated into Si-based wavelength-selective photodetectors operating at the wavelength of 1495.5nm, with a spectral linewidth of 2.0nm and a dark current of 40.1nA.