Study On MBE Growth And Physics Of Antimonide Laser And Detector Materials

Aiming at the optimization of AlGaAsSb/InGaAsSb multiple-quantum-well (MQW) lasers and detectors operating at 2μm wavelength band, the molecular-beam-epitaxy(MBE) growth and physics of the antimonide materials have been studied in this dissertation. The main results are as follows:The gain spectra of 2μm wavelength band InGaAsSb/AlGaAsSb strained MQW have been calculated. We also researched the effects of strain and the well width on the gain spectra. Results show that the model gain of the lasers can be improved by increasing strain or decreasing the well width.The optical confinement factor of the waveguide layer in the antimonide lasers has been calculated by using transfer matrix method in effective refractive index frame. Results show that waveguide thickness of 0.3-0.5μm is proper for 2μm wavelength InGaAsSb/AlGaAsSb lasers.The subband transition of In_xGa_1-xAs₀.02Sb₀.98 /Al₀.2Ga₀.8As₀.02Sb₀.98 quantum well laser structure has been investigated by using Kronig-Penny model under effective mass frame. The results show that InGaAsSb/AlGaAsSb is a suitable material system for 2-3μm quantum well lasers. However, the selection of suitable composition and the control of total strain are all very critical both in the structure design and in MBE growth. Based on above simulations, the design of the lasers has been optimized.High quality AlGaAsSb and InGaAsSb materials have been grown by using solid source MBE system on GaSb substrate. The research shows that appropriate substrate temperature and good surface treatment process are most important to materials growth. The strain in AlGaAsSb can be changed from compressive to tensile by adjusting the As composition. High quality composition graded AlGaAsSb materials have been grown bysolid source MBE, and its composition is changed from 0.2 to 0.4 gradually.The doping of the materials has been studied. The n type concentration in AlGaAsSb can be doped to about 6X 101?cm'3, whereas p type concentration can be doped to about 2 X1018cm"3. Te doping was used in InGaAsSb materials to compensate the higher hole background , and electron concentration can be controlled to n type of about 3 X 1016cm'3.The Photoluminescence (PL) measurements show that multiple quantum-well (MQW) materials have better fluorescence intensity because the thicker active zone and higher carrier density as well as better optical confinement, so MQW materials can operate under higher temperature and lower driving power. Ino.15Gao.85Aso.02Sbo.98 /Alo.2Gao.8Aso.o2Sbo,98 3QW materials have been grown by MBE with well thickness of lOnm and barrier thickness of 15nm. The materials show excellent PL at 2 um wavelength band.Ridge waveguide InGaAsSb/AlGaAsSb MQW lasers and detectors using the MBE materials have been fabricated. The lasers can be operated in continue wave mode at room temperature and the highest pulse operation temperature is above 90°C. The I-V characteristics and dark current of the InGaAsSb/AlGaAsSb PIN detectors have been improved evidently.