545 nm Room-Temperature Continuous-Wave Operation of BeZnCdSe Quantum-Well Green Laser Diodes with Low Threshold Current Density

Abstract

We report the growth of BeZnCdSe quantum-well laser diode (LD) structures with a short-period superlattice cladding layer and demonstrate continuous-wave lasing in the pure-green spectral region (545 nm) at room temperature. The threshold current density and voltage of a 5-µm-wide gain-guided laser were found to be 1.7 kA/cm2 and 10.4 V, respectively. This threshold current density is sufficiently low compared with that of InGaN/GaN green LDs.

Green/yellow luminescence from highly strained BeZnCdSe quantum wells grown by molecular beam epitaxy

“…5. Because our BeZnCdSe QW laser diodes in the green spectral region operated under a CW condition at room temperature [5], the PL spectra confirm the high optical quality of all the samples. To examine the microscopic uniformity of the luminescent characteristics, we obtained the PL images of the samples by using fluorescence microscopy.…”

“…Beryllium-containing ZnSe-based systems have a considerably higher degree of covalency than other II-VI compounds, and therefore, these systems are expected to have longer lifetimes [4]. Recently, we achieved room-temperature continuous-wave (CW) operation of BeZnCdSe quantum-well (QW) LDs on GaAs substrates at the longest wavelength in the green spectral region [5]. There is currently great interest in achieving extension of the lasing wavelength for the realization of yellow LDs using BeZnCdSe QWs.…”

Continuous-wave operation of green/yellow laser diodes based on BeZnCdSe quantum wells

“…The maximum power reaches 70 mW, when a reflectivity in a front facet is decreased to 70%. The output power in this LD is much improved, compared with our previous LDs with the maximum output power of 1.5 mW [10]. The main reason is that the effective band gap energy in SPSL is increased from 2.81 to 2.86 eV, indicating that carrier confinement in an active layer is improved due to higher barrier height.…”

“…This condition is applied to actual laser structure. Figure 3 shows the X-ray diffraction pattern (ω-2θ scan) of a wafer, from which we fabricated LDs and achieved continuous wave lasing at 545 nm [10]. A BeZnSe waveguide layer and a BeZnMgSe n-cladding layer are grown with lattice-mismatch less than 0.1%, while BeZnCdSe active layer is compressive strain of 2.2 %.…”

“…High-power lasing over 50mW at a peak wavelength of 536 nm was achieved. By employing highly strained BeZnCdSe quantum wells, cw lasing up to 570 nm has been achieved [10][11][12]. Figure 1 shows a layer structure for a green-yellow laser diode.…”