Fabrication And Characterization Of InAs Quantum Dot Lasers On Silicon

With the development of microelectronics,the number of transistors is dramatic increment,which lead to narrower spaces for electrical interconnects,higher power consumption and limited performances.In addition,the rapid development of the internet and internet of things(IOTs)generates huge amount of data to store and process in the data centers.However,traditional data centers are still using electrical interconnects which consume more power compared to optical interconnects.An interconnect solution with high speed,wide bandwidth,low power consumption is required to support the fast development of microelectronics.The silicon photonics combining the merit of optical interconnects and CMOS compatible,perfectly meets all of the criteria due its high speed,wide bandwidth,ultra-low transmission loss and low cost.At current stage,the efficient light sources on silicon are still a challenge.There are two major approaches to combine III-V materials with Si,which are wafer bonding techniques and direct epitaxial growth.The III-V/Si bonding method generally have scalability,yield and cost issues.In contrast,the direct growth method can overcome scalability and yield issues,which is the ideal approach for photonics integration if the high-quality III-V material can be achieved on Si substrate.In this work,we fabricated and characterized three different types of lasers through the high-quality InAs QD laser epitaxy structures directly grown on Si or SOI substrate.We first fabricated electro pumped Fabry-Perot(FP)cavity InAs QD lasers on Si.The threshold current of F-P cavity lasers on Si is 190 mA which corresponding to the current density of 265 A/cm~2.The full-width-half-maximum(FWHM)of the laser is0.1 nm.During the temperature dependent characterization,the laser can work at the temperatures ranging from-20?C to 65?C.In addition,it is found the laser performance influenced by the package technology.Secondly,we fabricated the InAs QD micropillar lasers on Si substrate.The lasing threshold of InAs QD micropillar is as low as 20?W with a FWHM of 1.3 nm under the optical pump power of 6 mW.Moreover,the micropillar laser is capable of operating at maximum temperature up to 100?C,which indicate the great temperature stability of InAs QD microcavity lasers on Si(001)substrate.As we known,all the silicon photonic devices are based on the SOI platform rather than Si substrates,however,III-V lasers on SOI platform by direct epitaxy remain absent in the field,which could potentially participate as an essential step towards the silicon photonic integration.In this work,we demonstrate the first O-band optically pumped InAs/GaAs QD microdisk laser on SOI substrates grown by molecular beam epitaxy(MBE).The quantum dot laser structures used for device fabrication were prepared by direct epitaxial growth on by dual-chamber MBE system.Additionally,the comparison of the performance of InAs QD microdisk lasers on GaAs,Si(001)and SOI are studied with identical epi-structures.The lasing threshold and Q factor of microdisk lasers on Si(0.38 mW,3674)and SOI(0.39 mW,3900)substrates exhibit similar performance in comparison with the lasers on GaAs(0.33 mW,3550),which indicated the high crystal quality of GaAs buffer on SOI.In summary,the work demonstrated in this thesis shown a great potential to integrate III-V lasers into silicon photonic platform for future photonic integration circuits applications.