Research On The Growth Of Multi-period InGaAs Quantum Dots Based On Patterned Substrates

Low-dimensional semiconductor materials have been favored by researchers for their superior performance in recent years,and quantum dot materials are also attracting the attention of researchers because of their superior photoelectric properties.Various types of quantum dot devices have gradually entered the sights of researchers and have been greatly developed since the 1990 s.The orderliness of quantum dots is an important factor affecting their photoelectric properties,ordered quantum dots can greatly improve the photoelectric properties of quantum dot devices,one of the main ways to achieve ordered growth of quantum dots is to use a patterned substrate.Patterned substrate technology nowadays includes using electron beam lithography to etch hole arrays on substrates,and changing the growth process to produce a buffer layer with a special morphology,former is more expensive but having better order of quantum dots,yet latter is less orderly but cheap and easy to implement.This paper mainly studied the method of manufacturing a buffer layer with special morphology,and surface structure of the multilayer quantum dot chains grown on it,as well as multilayer quantum dots grown on a patterned substrate etched by electron beam lithography.First,the process for the growth of multilayer quantum dots on a patterned substrate is determined,detailed process parameters are described below,6 ML deposition on a substrate at 505 °C at a deposition rate of 0.1 ML/s and annealing for 60 s with spacers of 40 ML and As pressure maintained at 5?torr during growth.Then a Ga As buffer layer with a strip-like island shape is successfully fabricated on a flat substrate,and single-layer and 8-layers,16-layers,and 24-layers multilayer quantum dot chains are grown.Size parameters of the quantum dots in each sample are theoretically analyzed.It is believed that the formation of such surface morphology is affected by incoherent quantum dots.The order of 16-layers is better than that of 8-layers and 24-layers,with fewer scattered dots and longer and more complete chains.Finally,based on experimental and theoretical analysis,a physical model of the surface morphology of quantum dot chains with periodic changes is established.In addition,quantum dots grown on a patterned substrate are studied,and single-layer,6-layers,12-layers,and 18-layers quantum dots are grown.The surface morphologies of the four samples were statistically analyzed,and the surface morphology is considered to be formed by the interaction of the ES barrier and incoherent quantum dots.It is foreseeable that after 18 cycles,the patterned substrate has little effect on the surface morphology of multi-cycle quantum dots.