Research On Functional Nano-patterned Substrate And Its Application In Integrated Optoelectronics

Integration of silicon-based microelectronic devices and III-V photonic devices can further increase the bandwidth capacity of the communications network and meet the demmands of upgrading.Currently,high quality integration of III-V material with Si mainly relies on the graded buffer layer to finish the heteroepitaxial growth,with the requirment of very thick buffer layer as well as precise composition control being the key disadvantages.With the gradual maturation of the nanofabrication technologies,the problems mentioned above may be solved using nano-patterned substrate.In addition,the luminescent properties of ?-? QW structures which have been most adopted in Si-based light emitting devices are greatly influenced by the threading dislocations(TDs).If zero dimensional quantum dot were adopted in active regions,dislocation tolerance of active region can be siginificantly enhanced,and the advantange of high characteristics temperature and low power consumption can be held by laser diode.Therefore,two aspects of research has been carried out in this thesis.The first one is using diblock copolymer to fabricate a nano-patterned Si substrate,while the latter one is the study on the growth of self-assembled InAs/GaAs quantum dots and fabrication of laser.The research results are as follow:1.Microphase separation of symmetric PS-b-PMMA on Si substrate was realized by solvent annealing method.After 16 hours thermal treatment at 25 ?,an ordered depression morphology with period of 90nm and PMMA column of 45nm in diameter was obtained from 45nm-thick copolymer film.The bottom morphology of the copolymer film was also characterized,which indicated that PMMA microdomains penetrate the entire film.2.InAs self-assembled quantum dots were deposited on In0.2Ga0.8As template by MOCVD.Growth temperature of 500?,very low growth rate of 0.03ML/s and ?/? ratio of 5 were adopted.Room-temperature photoluminescence spectra demonstrated the peak wavelength of GaAs-capped single-layer quantum dot(2.6ML)reached 1173nm and peak intensity was 1.8 times of that grown on GaAs template.3.Based on the results of single layer InAs QDs,a 5-stacked DWELL structure was also grown.InAs quantum dots grown on Ino.12Ga0.88As template were first capped by a 3nm-thick Ino.25Gao.75As followed by a 10nm-thick GaAs.Peak PL wavelength of the DWELL reached 1138nm and PL intensity was 1.4 times of that capped by 3nm-thick In0.12Ga0.88As layer.4.In cooperation with other people,pulse operation at room temperature of FP cavity laser containing 5-stacked DWELL structure was realized.Threshold current of 350mA and slope efficiency of 0.12W/A were recorded from the laser diode with 15?m-wide ridge and 500?m-long cavity.When injected with a pulse current of 500mA,peak output power of 18mW was reached.