Preparation And Optical-electronical Properties Of InSb Film On Si-based Substrate

InSb-based compound semiconductor material with high room temperatureelectron mobility has excellent electron transport properties under the action of anelectric field. InSb thin films have been used as photo detectors and imagingsystems in the mid infrared wavelength of3-5um since it has a smaller forbiddenband width. Further, InSb and its alloys light-emitting match the fundamentalabsorption lines of some of the main gas such as CO, CO2, etc. Thus InSb-basedlight emitting device and the detector member is made of a gas sensing system mayalso be used. In recent years, high-performance InSb structure has been grown on asilicon substrate, which combine the advantages of silicon and InSb to achieve theintegration of functional devices and circuits, therefore reduced the cost of thedevice, which became an important direction for the development of nano-scaledevices. In this study, InSb films and InSb/SiO2/Si XOI heterostructure aredeposited by magnetron sputtering, the crystal structure of the InSb thin film andInSb/SiO2/Si heterostructure was analyzed, combined with characterization of theoptical and XOI electrical properties, the relationship between the structure andproperties of material are studied in detail. The main content of this thesisincluding:The InSb target was prepared by vacuum arc, the normal stoichiometric ratio ofInSb film was completed by adjusting the target component. The structure andproperties of InSb film are studied under different sputtering process, with theincrease of the sputtering power, InSb film transited from amorphous to crystalline,the grain size increased, the crystallinity got better; on the contrary, when thesputtering pressure is gradually increased, the grain size became smaller, and thecrystallinity was poor. When the sputtering pressure is0.6Pa, the InSb film isIn-rich.As-deposited InSb films were preceded by rapid thermal annealing andconventional annealing; the influence of annealing process was studied. Thecrystallinity was improved with the rapid thermal annealing temperature increased,the grain size increased, and the preferred orientation of the (111) plane along wasalso enhanced. InSb film’s transmittance decreased with increasing temperature.When the annealing temperature increased from300°C to500°C, the optical bandgap of InSb changed from0.22eV to0.19eV. Hall measurements showed that thefilm annealed at77K and300K were n-type. Mobility and carrier concentration ofthe film had different levels of increasing as the annealing temperature raised. At a temperature of400°C, the grain size of film increased with rapid thermal annealingtime increased, the optical band gap gradually decreases. Film migration rateincreased with increasing annealing time at77K and300K, the carrier concentrationfirstly increased and then decreased lately with increasing annealing time at300K.Compared with the rapid thermal annealing process, the grain size of theconventional annealing film at the same temperature were larger than the grain sizeof the rapid thermal annealing film with the annealing temperature increased. Whenthe annealing temperature increased from200°C to400°C, the optical band gap offilm changed from0.22eV to0.2eV. The crystal quality was poor under500°Cconventional annealing, and the optical band gap increased to0.35eV. Comparisonof the two different annealing method shows that the mobility of the InSb film afterthe conventional annealing film with the exception of200°C annealed samples,were less than the sample treated by rapid thermal annealing. At a temperature of400°C, the InSb film grain size increases with conventional thermal annealing timeincreasing, the optical band gap red-shifted from0.24eV to0.2eV. The mobility ofthe films increased with annealing time decreased, the carrier concentrationincreased gradually with the annealing time. According to Avrami-Mehl-Johnsonformula and theoretical Arrhenian formula, the crystallization activation energy is131.5kJ/mol and66.9kJ/mol under rapid thermal annealing or conventional thermalannealing, respectively.InSb/SiO2/Si XOI heterostructure was grown by magnetron sputtering. TEManalysis shows that the thickness of InSb layer is35nm. The film after annealing isthe polycrystalline structure; the grain size is approximately13nm. Using ahigh-resolution transmission electricity microscope technology, the InSb film afterannealing is mainly along [111],[220],[311] three orientations, which is consistentwith the XRD analysis. HRTEM analysis revealed that the thickness of the SiO2layer is about4nm. InSb films annealed were influenced by the nano-scale quantumconfinement effect, the optical band gap of nano-scale InSb is blue-shifted about0.084eV and up to the0.264eV compared to the InSb crystal (0.18eV). From the I-Vcharacteristic measurement, it is shown that InSb/SiO2/Si XOI structure at ambienttemperature exhibited significantly diode rectifying characteristics. At roomtemperature, the turn-on voltage is0.35V, and then at77K it is0.55V. At300K, theelectron transport mechanism of InSb/SiO2/Si XOI structure is thermal electronemission recombination and diffusion mechanism when the voltage is less than0.35V; hot electron emission mechanism and space-charge local modes combinedeffect were mainly mechanism when the voltage is between0.35V and3V; as thevoltage is greater than3V, the local space-charge model mechanism is the mainly mechanism.