Low-density(~10^(9)cm^(-2)),long-wavelength(more than 1300 nm at room temperature)InAs/GaAs quantum dots(QDs)with only 1.75-mono-layer(ML)InAs deposition were achieved by using a formation-dissolution-regrowth method.Firstly,small high-density InAs QDs were formed at 490℃,then the substrate temperature was ramped up to 530℃,and another 0.2 ML InAs was added.After this process,the density of the InAs QDs became much lower,and their size became much larger.The full width at half maximum of the photoluminescence peak of the low density,long-wavelength InAs QDs was as small as 27.5 meV.
3.2 Wetting Layer Tailored by Epitaxial Stress Most epitaxial films wet the substrates to var-ying degrees in heteroepitaxy.In the paradigm systems of the QD epitaxial growth,In As/GaAs(001)and Ge/Si(001),the critical wetting layer(WL)for
This paper mainly describes fabrication of two-dimensional GaAs-based photonic crystals with low nanometer scale air-hole arrays using an inductively coupled plasma(ICP) etching system.The sidewall profile and surface characteristics of the photonic crystals are systematically investigated as a function of process parameters including ICP power,RF power and pressure.Various ICP powers have no significant effect on the verticality of air-hole sidewall and surface smoothness.In contrast,RF power and chamber pressure play a remarkable role in improving sidewall verticality and surface characteristics of photonic crystals indicating different etching mechanisms for low nanometer scale photonic crystals.The desired photonic crystals have been achieved with hole diameters as low as 130 nm with smooth and vertical profiles by developing a suitable ICP processes.The influence of the ICP parameters on this device system are analyzed mainly by scanning electron microscopy.This fabrication approach is not limited to GaAs material,and may be efficiently applied to the development of most two-dimensional photonic crystal slabs.
