GaN-based vertical-cavity surface-emitting lasers using n-type conductive AlInN/GaN bottom distributed Bragg reflectors with graded interfaces

Abstract

A 4.0λ-cavity GaN-based vertical-cavity surface-emitting laser (VCSEL) using an n-type conductive AlInN/GaN bottom distributed Bragg reflector (DBR) showed a light output power of 1.8 mW with a low differential resistance of 90 Ω. In order to obtain low resistive AlInN/GaN DBRs, 5 nm AlGaInN graded interfaces were introduced. A 40-pair AlInN/GaN DBR with the graded interfaces showed a peak reflectivity over 99.8% and a series resistance of 17 Ω. At the same time, the maximum light output power of a 1.5λ-cavity GaN-based VCSEL with the conductive DBR was only 0.03 mW due to a high thermal resistance of 2700 K W−1 caused by a high thermal resistivity of AlInN. We also conclude that a short cavity typically used in GaAs-based VCSELs is not appropriate in GaN-based VCSELs.