Study Of Effects Of External Stress Field On The Properties In InAs/GaAs Quantum Dots

With the development of the semiconductor industry and the rise of low-dimensional semiconductor materials,there are increasing demands on semiconductor materials.Semiconductor materials such as quantum dots and quantum wells are widely used in technologies such as computers,mobile phones,lasers and satellites because of their excellent optoelectronic properties.The optical and electronic properties of semiconductor quantum dots have been studied in many theories and experiments,but due to the high application demands of quantum dots materials,the properties are still to be investigated.The properties of semiconductor quantum dots can be improved by improving the growth process and applying external fields,such as stress field,temperature field,electric fields and magnetic field,to satisfy the requirements of high performance of quantum dots devices.In order to investigate the influences of mechanical stress on optical properties and energy band structure,and adjust the optical properties of semiconductor quantum dots materials,we investigated the energy band and strain changes of InAs/GaAs quantum dots under mechanical stress using k·p model and analytical calculation,and gave a method for band gap and strain adjusting.Firstly,we established a stress-energy band theoretical model through the k·p model,and gave the relationship equation between mechanical stress and energy band based on the k·p model.The changes in the heavy hole,light hole and spin hole of the InAs/GaAs quantum dots material were investigated when mechanical stress was applied,and it was found that the energy band of the spin hole changed most significantly and the light hole changed least when the same mechanical stress was applied.We changed the magnitude of the applied mechanical stress and obtained the same results.Secondly,due to the effects of strain on energy band structure,we calculated the factors influencing the strain.We have investigated the effects of mechanical stress and aspect ratios on the strain of pyramidal InAs/GaAs quantum dots by analytical calculation.The results of the analytical calculation showed that the aspect ratios changed the biaxial stress inside the quantum dots material,and the biaxial strain increased with the increasing of the aspect ratios.The strain also increased by applying mechanical stress.It means that both increasing the mechanical stress and the aspect ratios can increase the strain of the material.Finally,we applied the mechanical stress to the strain of shear direction,we calculated the shear stress of the InAs/GaAs quantum dots and applied different mechanical stresses,the calculation results showed that the trend of shear strain was same as the conclusion of positive strain.It means that the shear strain will also increase with the increasing mechanical stress,and that we can modulate the material properties by applying mechanical stress.We can change the mechanical stress and aspect ratio to adapt the material properties to realistic needs.So far,we have established stress-energy band and aspect ratio-stress-strain calculation models by analytical calculations,which provide a calculation method to adjust the optical properties of the material to the ideal range and provide a theoretical method for the adjusting of the optical properties of semiconductor quantum dots.