Theoretical And Experimental Investigation On The Heterogeneous Compatibility Issues Of Optoelectronic Semiconductor Material

The research work of this doctoral thesis was mainly supported by thesubproject one "Theory on heterogeneous materials compatibility and Keystructure&Technology Innovations for Monolithic Integrated OptoelectronicDevices "(Project No.2003CB314901) , which belongs to the "BasicResearch on Integrated Optoelectronic Devices and Microstructure OpticalFibers with Structure and Technology Innovations for Future AdvancedOptical Communications", National Basic Research Program ofChina(Project No.2003CB314900) , which Professor Ren Xiaomin isresponsible for as a chief scientist. Additionally, Part of research was alsoassisted by the project "Material Technology Research on GaAs andInP-based Functional Tapered Structure and Applications in NovelOptoelectronic Devices", the National Natural Science Foundation ofChina(Project No.90601002)Novel integrated optoelectronic devices are prerequisite to the evolutionof the optical communications systems. And the major outstanding issues,which have been encountered with during the investigation of integratedoptoelectronic devices, are compatibility of semiconductor materials, that ofstructures and that of processes. And how to realize the successfulcompatibility of heterogeneous semiconductors integration is the mostimportant scientific issue. In this doctoral thesis, a great deal of researchwork has been done. That is mainly focused on the compatibility issues ofheterogeneous materials. Research results, as listed below, have beenachieved. 1．Band structures of BP,BAs,BSb are calculated, the energy gaps intheir high symmetric points(Γ, L, X) are obtained, by comparison withthe experimental value, the calculated errors are evaluated, these will bethe basis for the calculation of band structure of ternary alloys.2．The electronic properties of BGaAs and BGaSb alloys arecalculated in the low boron composition (0%-18．75%). For BGaAs,a small and composition-independent direct transition (Γ-Γ) bowingparameter of 2．6eV is obtained, with addition of small boron, the directgap increases by～19meV/B%; For BGaSb, the bowing parameterof direct transition (Γ-Γ) is 2．1eV, with addition of small boron, thedirect gap increases only by～7meV/B%. Comparison of theirformation enthalpies of mixing predicts that BGaSb films with boroncomposition of at least 6% are possible.3．Direct transition (Γ-Γ) and indirect transition (X-Γ) bowingparameters of ten ternary alloys have been calculated, based on theseresults, the band structure of six kinds of quartery alloys includingBGaAsSb et al. are analyzed with their lattice matched to GaAs,indicating that the direct transition (Γ-Γ) of BGalnAs,BInPSb,BInAsP may reach 0．8eV, which corresponds to 1550nm band-edgeemission of the optical communications, such material systems providea new choice for the development of GaAs-based long-wavelengthoptoelectronic integration devices.4．Based on InP/GaAs(100) heteroepitaxy by low temperature(LT) bufferlayer, inserting SLS in normal InP epilayer can dramatically improvethe quality of InP epilayer, for 1．2μm thick InP/GaAs(100) epilayers,the FWHMs of XRD (400)ω-2θandωscans are 325arcsec, 371arcsec,respectively; and for 2．6μm thick InP/GaAs(100) epilayers thecorresponding FWHMs are 203arcsec and 219arcsec, the calculateddislocation density is 10 cm, TEM indicates the SLS effectivelyreduce the density of threading dislocation in epilayers. 5．Ten periods of InP/InGaAs MQW are successfully grown onInP/GaAs(100) heteroepitaxial layers, the XRDω-2θscans showdistinct satellite peaks, the period thickness calculated by the angularseparation of satellites are consistent with the designed value, roomtemperature PL shows band-edge emissions of 1625nm, its FWHM is47meV, the optical properties of heteroepitaxial MQWs can competewith those of MQW on InP substrates, these results indicates thequality of InP/GaAs(100) epitaxial layer has meet with the demand ofOEIC devices.6．By low temperature buffer layers InGaAs/InP PIN photodetectors aregrown on GaAs(100) substrates, the photodetectors with 300nm-thickInGaAs adsorption layer show a typical responsivity of 0．12A/Wto 1550nm optical radiation, corresponding to an external quantumefficiency of 9．6%, photodetectors with the active area of 50μm×50μmexhibit-3dB bandwidth reaching 6GHz.7．GaAs/Si(100) heterostructures are prepared by optimizing the growthconditions of LT GaAs, for 1．8μm GaAs epilayers, the FWHMs ofXRD(400)ω-2θandωscans are 440arcsec and 503arcsec, respectively;Si(100) 4°slanting to(110) substrates can greatly improved the qualityof GaAs epilayers, for the same thickness of 1．8μm, the correspondingFWHMs of XRD measurements are 298arcsec and 338arcsec,respectively, the FWHM of XRDωscan for 3．5μm thick epilayer isonly 216arcsec, its TEM shows little threading dislocations inepilayers.In June of 2005, the 973 Program was mid-evaluated by the Ministry ofScience and Technology of the People's Republic of China, it was praisedfor the outstanding and innovated achievements (including the aboveresearch results in this paper), and 200 million yuan was added to the 973Program fee. In addition, One achievement of our group named "High-speed,narrow-linewidth and tunable integrated optical demultiplexing and receiving device and its key fabrication technologies" has been selected asone of the Year 2006's Chinese ten greatest science and technologiesprogresses of the university and colleges, and has won second class ofBeijing science and technologies awards, at present, State technologyinvention second class awards was applied, which was under review;however, the above achievement was realized by bonding technology whichbelongs to quasi-monolithic integration, while GaAs-based InGaAs/InP PINphotodetectors are kinds of monolithic integration, it indicates the newimportant progress of our group's work.