Investigation On The Novel Material Systems Theory And Metamorphic Growth For Optoelectronic Integration

The research work of this doctoral thesis is mainly supported by such projecets as listed below. National High-tech Research and Development Program of China (863Program)"The innovative researches of III-V optoelectronic materials with boron incorporated for monolithic integrated"(Project No.2009AA03Z417),"The exploration of novel materials and special superlattice structures for heterogeneous semiconductor compatibility"(Project No.2010CB327602), which belongs to Major State Basic Research Development Program (973Program)(Project No.2010CB327600) and the "111" Project of China (No.B07005).The development of the new generation of optical communication systems demands high speed and integration for novel communication optoelectronic devices. The change of optoelectronic devices from division to integration will bring important revolution to optical fiber communication. The compatibility of heterogeneous materials is the most outstanding issue for communication optoelectronic integration. Novel optoelectronic material forecast and metamorphic growth are important ways to solve this bottleneck. The thesis focuses on the novel material system theory and InP/GaAs metamorphic growth for monolithic optoelectronic integration. The main contents and achievements are as follows.1. The first-principle calculations based on density functional theory are performed using a special quasirandom structure (SQS) approach. The structural, electronic and optical properties of BxGa1-xAs alloy are investigated. The variation of band gaps and band gap bowing parameters (2.57eV～5.01eV) are discussed. The temperature-composition phase diagram is analysed. The maximum mixing enthalpy is161.99meV/atom. The results indicate the BxGa1-xAs alloy is difficult to synthesis for normal grown temperatures.2. The electronic and optical properties of the quaternary BGaInAs and BGaAsSb alloy lattice-matched to GaAs are investigated numerically. The stability of configurations with different doping atoms distribution are investigated. The effect of the B, In and B, Sb incorporation on band gaps is analyzed. The variation of optical properties including dielectric function, absorption coefficient, reflectivity, refractive index and energy loss function of the alloy are also discussed.3. The structural and electronic properties and formation energies of ternary GaP1-xNx dilute alloy are investigated. The investigation of thermal stability shows that (000)(222) and (000)(011)(222) distributions are the most stable configurations at x=6.25%and9.375%, respectively. The unit cell volume exhibits a large and negative deviation from Vegard’s law. The GaP1-xNx presents the characteristic of a direct band gap at x=3.125%and the incorporation of N strongly reduces the band-gap energy.4. The electronic and optical properties of ternary GaN1-xBix and InP1-xBix dilute alloy are calculated. The results indicate that the band gaps of the alloy reduce with the increasing of Bi. The band gaps of GaN1-xBixand InP1-xBix decrease by227meV/%Bi and89meV/%Bi, respectively. The absorption coefficient, reflectivity, refractive index and conductivity of GaN show the significant changes induced by the incorporation of Bi.5. Heteroepitaxial growth of InP/GaAs are prepared and discussed by optimizing the growth conditions. Low temperature InP buffer and inserting strained layer superlattice on normal InP epilayers are adopted. The InP epilayers are grown by optimizing low-temperature GaAs and InP buffer layers, the FWHMs of XRD ω-2θscan is443arcsec. Inserting the strained layer superlattices into normal InP epilayers can obviously improve the quality of epilayers, the FWHMs of XRD ω-20scan is340arcsec. In addition, compositionally graded metamorphic buffers including linear and stepped for compositionally graded InGaP and InGaAs buffers are obtained. The effects of this scheme on reducing the threading dislocation in InP epilayers are investigated.