Analysis Of Light Emission Performance Of Peseudoheterostructure Diode Based On Suspended Micro-bridge Structure

With the rapid development of microelectronics technology,the transistor density in integrated circuits is increasing.However,with the decrease of the transistor size,the computational speed of integrated circuits has now become limited by the increased power consumption caused by electrical interconnects.In order to solve the performance bottleneck of the integrated circuit,on-chip optical interconnect system has attracted more and more attention.Over the past decade,many of the key components of the on-chip optical interconnect system have been achieved,such as high-performance photodetectors and modulators.However,an efficient Si-based light emission source remains challenging.Since Si and Ge are indirect band gap materials,the light emissions properties are much lower than those direct band gap materials.Recently,the studies have shown that the light emissions properties of Ge can be improved by introducing tensile strain.In this thesis,we first introduce the basic theory for band structure calculation,including perturbation theory and kp theory.Then,we construct the Hamiltonian of bulk material under the strain condition,and calculate the band structure of Germanium by 8kp method under the biaxial and uniaxial tensile strain.The effect of strain on the effective mass is obtained by analyzing the constant-energy surface.Then the strain distribution of suspended micro-bridge structure is analyzed.Since the strain distribution is not uniform,the micro-bridge structure will natural form a pseudoheterostructure diode.The transport properties of the pseudoheterostructure diode are simulated by the drift-diffusion model.The relationship of the carrier density and the injected current density can be obtained by the simulation.Finally,we introduce the theory of radiative and non-radiative recombination,and investigate the influences of strain,doping density and injected carrier density on spontaneous emission rate,internal quantum efficiency and transparency current density.An internal quantum efficiency around 9% and transparency current density of25.8k A / cm can be obtained with doping density of18 35 10 cm-× and transparency carrier density of18 32 10 cm-× when uniaxial tensile strain is 4%.The result indicates the pseudoheterostructure diode based on the Ge micro-bridge can be used to realize an efficient electrically driven Si-based light emission source.