Research On Metamorphic Growth With Nano-Patterned Substrates And Ⅲ-ⅤSelf-Assembled Quantum Dots

With the acceleration of global informationization, the demand for bandwidth is increasing, which has promoted the development of optical communication and put forward higher requirements for the cost and performance of the existing optoelectronic devices. Obviously, the traditional photoelectron discrete devices are not able to meet the development of communication technology. Photoelectric integration can make the devices smaller, the packaging costs cheaper and the performance of the system more stable, which has become the developmental trend of optoelectronic devices. However, it has been the most important technical barriers to solve the problem of metamorphic growth between different materials.In addition, quantum well or superlattice used as the active region of communications optoelectronic devices (especially lasers) has several disadvantages. Quantum dots are of great significance as a new structure, which make the devices operate at lower threshold current density with higher temperature stability due to the three-dimensional carrier confinement.Therefore, the main work is about two aspacts. InP epitaxial layer was deposited on the nano-patterned GaAs substrate formed by silicon nanospheres and GaAsP was inserted as a strain-reducing layer for the multi-layer quantum dots experiment. The research results are as follows:1. Single monolayer distribution of silica nanospheres was realized on GaAs(100) substrate by spin coating, and thus nano-patterned substrate with area larger than1OOμm×100μm was obtained. In the experiments, silica nanospheres had the diameter of-460nm, the dilution ratio with anhydrous ethanol was set to1:3, the spin speed was set to2500r/min and the spin duration was set to30s.2. The nano-patterned GaAs substrate was successfully used for InP metamorphic growth. SEM, TEM and XRD measurements were applied for the InP/GaAs metamorphic samples and the corresponding comparisons with metamorphic samples on the nonpatterned substrate had been carried out. It has been found that silica nanospheres blocked the propagation of threading dislocations (TDs). The FWHM of InP (004) diffraction peak was decreased from394arcsec to328arcsec, which demonstrated the improvement of crystallinity for metamorphic InP.3. InAs quantum dots were grown with very low growth rate of0.04ML/s at500℃by MOCVD. The V/III ratio was10and the InAs coverage was3ML. Room-temperature photoluminescence measurement demonstrated the great improvement in luminescence properties with a linewidth of36meV at1248nm peak wavelength.4. High-quality multi-stacked InAs/GaAs quantum dots were obtained by the insertion of8nm GaAs1-xPx (x=0.2) strain compensation layer and the acceleration of temperature-changing process. The growth rate of InAs QDs was about0.03ML/s at480℃and the growth time was90s with a Ⅴ/Ⅲ ratio of10. The PL intensity has been greatly enhances, which is more than3times higher than that of single-layer QD sample.