Use of aluminum-free epitaxial structures for near-infrared laser diodes has been an active research area in the past decade. These edge-emitting laser diodes have demonstrated operational lifetimes exceeding 10,000 hours at high output powers and high efficiencies. Improvements in epitaxial structure, processing, and packaging have enabled these results. In this paper, we will review developments in aluminum-free laser diodes. We describe our recent work with these devices and conclude by discussing reliability issues.
ZnSe-based laser diodes have recently encountered strong competition from those grown from GaN related materials. These two material systems behave in a very different way as far as defect generation and propagation are concerned. For ZnSe-based materials the lifetime of a laser-diode is very sensitive to the density of pre-existing extended defects in the epitaxial material. Therefore, fabrication of a long- lived ZnSe-based laser diode requires an elimination of extended defects as well as making low-resistivity components in order to minimize device heating. We discuss the molecular beam epitaxy growth and characterization of ZnSe-based epitaxial structures on various III-V buffer layers lattice matched to GaAs. The status of our ZnSe-based laser diodes and microcavity LEDs will also be discussed.
This paper presents the performance characteristics and reliability data of GaInAsP- and AlGaInP-based laser diodes emitting at the wavelengths from 650 to 1,300 nm. The lasers are grown by toxic-gas-free all-solid-source molecular beam epitaxy (SS-MBE).
Spectroscopic work is reviewed which focuses on the microscopic mechanism of gain in ZnSe-based quantum well (QW) lasers, under optical and electrical injection, respectively. Excitonic processes are rather distinct at cryogenic temperatures in the strongly quasi-2 dimensional case of a ZnCdSe QW. More strikingly, recent studies on the room temperature diode lasers show that electron-hole pairwise Coulomb correlations remain relevant in this case as well.
We report the molecular beam epitaxial growth of the quaternary (Zn,Mg)(S,Se) compound as well as the incorporation of this quaternary into a pseudomorphic SCH blue-green laser diode configuration. X ray diffraction and TEM imaging indicate that the quaternary (Zn,Mg)(S,Se) can accommodate substantially more strain than the binary ZnSe; pseudomorphic epilayers with thickness of about 2 micrometers could be grown within a strain range of -0.225% (tension) and 0.137% (compression) at room temperature. Room temperature continuous wave operation of diode lasers having the quaternary as cladding layers was achieved with a lifetime of longer than 20 seconds. These index-guided laser diodes, employing the Zn(Se,Te) graded ohmic contact (adopted to contact p-type (Zn,Mg)(S,Se), have provided a significant reduction in lasing threshold voltage to 4.2 V.
The planar doped barrier diode being majority carrier semiconductor device has promising application areas in high-frequency and microwave circuits. The paper reviews the main features of diode structures. The different current conducting processes as the thermionic emission, the diffusion, and the tunneling are treated. The design rules for the barrier height also are given, and our own experimental results reported. Microwave diodes and zero bias detectors have been fabricated in RITP on layer structures grown in TUT.
This paper deals with growth of GaAs InP and their ternaries quaternaries and heterostructures by the gas-source molecular beam epitaxy (GSMBE) method. Epilayer qualities are discussed and compared with those obtained by other methods. Some problems related to growth of layers and interfaces are discussed in detail. Properties of lasers photodetectors and optical modulators fabricated by GSMBE are presented.