Disordering by Diffusion of Impurities in InGaAs/AlGa/GaAs Multiple Layrs and Its Application to Vertical Cavity Surface Emitting Micro Lasers

Conventional surface emitting laser是usually fabricated by mesa etching to reduce thresholdcurrent,and the electrode is formed on the part of the light emitting surface.这些差异集成电子元件元件组件，也可用于laser区域，which is not desirable for high density integration OEIC and 2 dimensional laser array monolithicchips.In the study，a novel structure based on TJS planar laser形式on semi-insulating substrate are proposed for theplanar micro surface emitting laser fabricated by impurity disordering in superlattices. The main(1) A novel structure for A planar micro surface emitting laser：laser structure has lateral conducting n and p layrs，which is inserted between GaAs/InGaAs/GaAs strained quantum well layrs and AlAs/GaAs DBR multiple反射器layrs in the TJS laser structure. Carrier injection is uniform in the quantum wells whichovercomes the Joule heating due to high se…更多ries resistance through hetero barriers of AlGaAs/GaAs multiple reflectors as found inconventional结构。(2)Fabrication of the layr结构ucture of the laser by MBE with water coolingmethod:The layr structure of The laser is strained single quantum well GaAs/InGaAs/GaAs sandwiched with 24AlAs/GaAs quarter wavelength DBRs，计算机控制器MBE system with water cooling （not using liquid nitrogen）cooling as in conventional one . A high efficient 0.98 mum photoluminescence for 8nm thickin__ <0.2> ga__ <0.8>As is observed at room temperatire comparable with those of MOCVD growth.(3)Diffusion of Si and Zn under As pressure：Zn and Si are chosen as the impurities for the superlattices. the films for diffusionare deposited on wafers by electron beam from sio_2 contained Zn or pure Si. After deposition, After depositionwafers are annealed at 600c for Zn and 850c for Si diffusion.这是发现Si diffusion isenhanced under As pressure in an evacuated quartz tube，diffusion depth is 4mum for 20hr at 850C.(4) Doping of conducting p and n GaAs layrs：n类型conducting layrs by Si dopant and p类型consuction layrs by Be doping are grown by theMBE,and the electron mobility exceed 2000cm ^2/ v.s for typical donor conncenntration of 7x10^<17>cm <-3> with the background other impurities less than 1x10^<17> cm^<-3>. Hole mobilities ofBe-doping wafers are almost coincident with those of p-doping level between 10^<18> and 5x10^<18>cm . These results show that the wafers will be used for lasers with carrier injection level of10^<18> cm^<-3> or more.(5) Disordering of superlattices：Wafers with (24 AlAs/GaAs DBR) / (p-GaAs conducting layr) / （GaAs/InGaAs/GaAs strained double）quantum wells) / (n conducting GaAs layr) / (5-10 AlAs/GaAs DBR)，for micro laser structure are grown by the MBE with a计算机控制器系统successfully. Sibas been diffused under As pressure at 850c for 20hr in an evaquated quartz tube，其中followed by Zn diffusion at 600c for 4 hr using SiN films for diffusion masks. Both Si and Zn已被监测的SEM，其中包括适用于planar fabrication微surface发射laser with low threshold. Less

Conventional surface emitting laser is usually fabricated by mesa etching to reduce threshold current, and the electrode is formed on the part of the light emitting surface. These difficulties to integrate electrical elemental devices such as FETs and also reduce the area of the laser, which is not desirable for high density integration OEIC and 2 dimensional laser array monolithic chips.In the study, a novel structure based on TJS planar laser formed on semi-insulating substrate are proposed for the planar micro surface emitting laser fabricated by impurity disordering in superlattices. The main results obtained are as follows.(1) A novel structure for a planar micro surface emitting laser : The laser structure has lateral conducting n and p layrs, which is inserted between GaAs/InGaAs/GaAs strained quantum well layrs and AlAs/GaAs DBR multiple reflector layrs in the TJS laser structure. Carrier injection is uniform in the quantum wells which overcomes the Joule heating due to high se … More ries resistance through hetero barriers of AlGaAs/GaAs multiple reflectors as found in conventional structures.(2) Fabrication of the layr structure of the laser by MBE with water cooling method : The layr structure of the laser is strained single quantum well GaAs/InGaAs/GaAs sandwiched with 24 AlAs/GaAs quarter wavelength DBRs, which are formed by computer controlled MBE system with water cooling (not using liquid nitrogen cooling as in conventional one). A high efficient 0.98 mum photoluminescence for 8nm thick In_<0.2>Ga_<0.8>As is observed at room temperatire comparable with those of MOCVD growth.(3) Diffusion of Si and Zn under As pressure : Zn and Si are chosen as the impurities for disordering of the superlattices. The films for diffusion are deposited on wafers by electron beam from SiO_2 contained Zn or pure Si. After deposition, the wafers are annealed at 600 C for Zn and 850 C for Si diffusion. It is found that Si diffusion is enhanced under As pressure in an evacuated quartz tube, and the diffusion depth is 4mum for 20 hr at 850C.(4) Doping of conducting p and n GaAs layrs : n type conducting layrs by Si dopant and p type consuction layrs by Be doping are grown by the MBE,and the electron mobility exceed 2000 cm^2/V・s for typical donor conncenntration of 7x10^<17> cm^<-3> with the background other impurities less than 1x10^<17> cm^<-3>. Hole mobilities of Be-doping wafers are almost coincident with those of p-doping level between 10^<18> and 5x10^<18> cm^<-3>. These results show that the wafers will be used for lasers with carrier injection level of 10^<18> cm^<-3> or more.(5) Disordering of superlattices : Wafers with (24 AlAs/GaAs DBR) / (p-GaAs conducting layr) / (GaAs/InGaAs/GaAs strained double quantum wells) / (n conducting GaAs layr) / (5-10 AlAs/GaAs DBR), for micro laser structure are grown by the MBE with a computer controlled system successfully. Si bas been diffused under As pressure at 850C for 20 hr in an evaquated quartz tube, which followed by Zn diffusion at 600C for 4 hr using SiN films for diffusion masks. Both Si and Zn disordering have been observed by SEM,which are conirmed to be applied for fabrication of planar micro surface emitting laser with low threshold. Less