Development of yellow‐green LEDs and LDs using MgZnCdSe‐BeZnTe superlattices on InP substrates by MBE

Abstract

PACS 42.55.Px, 73.40.Lq, 85.60.Jb We have fabricated yellow-green light emitting diodes (LEDs) and laser diodes (LDs) by using II-VI compounds grown on an InP substrate. A separate confinement hetero-structure was fabricated by means of Cl-doped MgSe/ZnCdSe SuperLattices(SLs) for n-side layers, a ZnCdSe Single Quantum Well (SQW) for an active region, and N-doped MgSe/BeZnTe SLs for p-side layers. Lasing emission around 560 nm could be observed at a current density over 2.5 kA/cm 2 under the pulsed current injection at 77 K. In order to obtain a lasing operation at room temperature, it is necessary to decrease the resistance of the LD and to suppress the current leakage at the interface between the active region and the p-side region.1 Introduction II-VI compound semiconductors are very attractive as materials for visible light emittors, since their bandgap energies can cover the whole visible light range. Various semiconductor laser materials and structures have been proposed to date. Among them, only II-VI LDs can operate in the yellow-green wavelength region. In the case of MgZnSSe based LDs grown on GaAs substrates, a lasing emission was observed in a blue-green light region around 500 nm under the continuous wave operation at room temperature (RT) [1]. Moreover, recently ZnCdSSe and CdSe quantum dots based LDs have also been proposed [2,3], of which lasing wavelengths were from 500 nm to 560 nm at RT. Although these LDs grown on GaAs show relatively good performances, degradation still remains as a serious problem. We have proposed II-VI compounds on InP substrates instead of ones grown on GaAs in order to overcome the device degradation problem. Because the II-VI material system on InP does not have any strain in the active layer, the device structure can be designed under lattice matching to InP, which would be powerful candidates for a long-lived device. Some groups have also reported MgZnCdSebased light emittors on InP [4][5][6][7]. However, thus far no groups have succeeded in lasing-operation by the current injection scheme. This failure is due to the lack of suitable p-cladding materials for LDs. We have proposed a BeZnTe ternary alloy [8] and related materials [9, 10] as a new p-cladding layer and visible LEDs and LDs were successfully fabricated.In this paper, we describe LED and LD structures based on the II-VI materials grown on InP, as well as what structures might be suitable for visible LED and LD with these materials. We then explain our experimental results of the ZnCdSe single quantum well (SQW) LDs.

Growth of ZnTe Semiconductor Crystal Via a Te Flux Zone Melting Method and Characterization of Its Properties

“…[1,2] Besides, ZnTe crystal can be used for pure green light emitting diodes (LED) fabrication because the electroluminesence at 550 nm was DOI: 10.1002/crat.202100279 realized. [3][4][5] Moreover, ZnTe crystal is also considered as a competitive material for electro-optical modulator and mid-infrared laser device production. [6,7] Therefore, the preparation of large size and high quality ZnTe crystal has become an urgent goal.…”