Effect of a tensile-strained InGaP electron stopper layer for 1.3-μm InGaAsP/InP strained multiple quantum well lasers

• Main Authors: TJ Wang, 王泰鈞
• Other Authors: 黃滿芳
• Format: Others
• Language: zh-TW
• Published: 2006
• Online Access: http://ndltd.ncl.edu.tw/handle/65695049651071740267

碩士 === 國立彰化師範大學 === 光電科技研究所 === 94 === In this thesis, the effect of the different position of a tensile-strained InGaP electron stopper layer (ESL) on 1.3-μm InGaAsP/InP compressive-strained multiple-quantum-well (MQW) ridge waveguide laser diodes (LDs) was investigated. InGaAsP/InP material is the most popular material for fabricating light sources in long-haul fiber communication applications. However, InGaAsP/InP LDs show poor temperature characteristics partly owing to large Auger recombination rates existed in this low bandgap material system and partly owing to poor electron confinement resulted from the small conduction-band offset (△Ec=0.4△Eg). One can expect that the temperature characteristics can be improved by introducing ESL between the MQW active layer and p-cladding layer to suppress the electron overflow from the MQW to the p-cladding layer. The characteristics of InGaAsP LDs with ESL located at two different positions are compared with the characteristic of the laser without ESL. One ESL is inserted between the p-InP cladding layer and p-side separated confinement heterostructure (SCH) layer. The other one is inserted between the MQW and p-side SCH layer. Theoretical analysis is perfromed using the LASTIP simulation software with the consideration of valence band mixing. Simulation results show that the threshold currents and slope efficiencies of the lasers with an ESL, especially located at the interface between the p-cladding layer and SCH layer, are greatly improved. The characteristic temperature is improved from 73 K to 83 K. This indicates that electrons are blocked effectively by the ESL. Moreover, this tensile-strained InGaP ESL is chosen so that the light hole band of this ESL is split from the heavy hole band and aligned with the valence band of the p-InP cladding layer. Therefore, the blocking of holes owing to this ESL can be minimized. On the other hand, the characteristics of the LD with an ESL layer inserted between the MQW active layer and p-side SCH layer is worse, especially at high temperature and high operation power. One of the reasons is due to that overflow electrons are confined within the SCH region between the ESL and p-cladding layer. These confined electrons are increased as injection current and operation temperature are increased. Another reason is that the barrier height of the valance band of ESL is about 75meV which suppresses hole injection from the p-SCH layer to the MQW region. Finally, we also studied the the characteristics of LD with an ESL inserted at different positions of p-cladding layer and found out that the best position for a tensile-strained InGaP ESL is to insert at the interface between the p-cladding layer and SCH layer.