Room-temperature continuous-wave operation of BeZnCdSe quantum-well green-to-yellow laser diodes with sub-10 mA threshold current

Abstract

Low threshold current BeZnCdSe single quantum-well (SQW) laser diodes (LDs) have been developed. The waveguide was formed of a ridge structure with etching away the top p-type BeMgZnSe/ZnSe:N short-period superlattice cladding layer, and then covered with a thick SiO 2 layer and planarized with chemical-mechanical polishing and reactive ion etching process. Three type LDs with different SQW thickness and Cd content were developed and compared at varying waveguide width and length. Lasing wavelength of 535, 563, and 567 nm were realized respectively, at room-temperature continuous-wave condition with the laser cavity formed by the cleaved waveguide facets coated with high-reflectivity dielectric films. Compared with our previously developed gain-guided diode structure for a 5-μm-wide, 800- μm-long gain-guided green laser with a threshold current and voltage of 68 mA and 10.4 V, a 535-nm green laser with 7- nm-thick SQW can realize a threshold current and voltage of 7.07 mA and 7.89 V, respectively, for a cavity width of 4 μm and length of 300 μm. A 563-nm yellow LD with 4-nm-thick SQW was also developed with 7.4-mA and 8.48-V threshold current and voltage for a 3-μm-wide, 300-μm-long cavity. A 567-nm yellow LD with 7-nm-thick SQW can achieve a threshold current and voltage of 10.8 mA and 8.4 V, respectively, for a cavity length of 300 μm and width of 7 μm. The threshold current and voltage were decreased due to the reinforced confinement of carriers in cavities. The device performance can be significantly improved with much lower power consumption. The threshold current and power consumption is also sufficiently low compared with that of InGaN/GaN green LDs, which will benefit the potential application for ZnSe-based LDs as light sources in full-color display as well as some biomedical devices.