Group II-VI compound semiconductor light emitting devices which include at least one II-VI quantum well region of a well layer disposed between first and second barrier layers is disclosed. The quantun well region is sandwiched between first and second cladding layers of a II-VI semiconductor material. The first cladding layer is formed on and lattice matched to the first barrier layer and to a substrate of a III-V compound semiconductor material. The second cladding layer is lattice matched to the second barrier layer. The quantum well layer comprises a II-VI compound semiconductor material having the formula AxB(1-x)C wherein A and B are two different elements from Group II and C is at least one element from Group VI. When the second cladding layer has a p-type conductivity, a greaded bandgap ohmic contact according to the present invention can be utilized. The graded bandgap contact can be a single continuously graded II-VI p-type region or a plurality of cells with each of the cells having first and second thin layers of first and second p-type II-VI semiconductor materials respectively. Another embodiment of the present invention discloses a monolithic multicolor light emitting element capable of emitting four colors and a method for fabricating same. The monolithic multicolor element includes four II-VI semiconductor light emitting devices formed on a single III-V substrate.

Group II-VI compound semiconductor light emitting devices and an ohmic contact therefor

Cd1-xBexSe and Cd1-xMgxSe solid solutions were grown from the melt by the high pressure Bridgman method. Optical, luminescence and photothermal properties of these materials were investigated. Spectroscopic ellipsometry was applied for determination of the spectral dependence of the complex dielectric function (E) and refractive index n(E) at room temperature in the photon energy range 0.75-6.5 eV for samples with optic axis (c-axis) perpendicular to the air-sample interface. The critical point (CP) parameters for E0 and E1 transitions were determined using a standard excitonic CP function to fit the numerically calculated differential spectra ∂2e2/∂E2. The dispersion of the refractive index of the alloys was modelled using a Sellmeier-type relation. The values of fundamental and exciton band-gap energies were estimated from the ellipsometric and photoluminescence measurements. The origin of luminescence in Cd1-xBexSe and Cd1-xMgxSe was discussed. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

https://onlinelibrary.wiley.com/doi/pdf/10.1002/crat.200410355

Growth and optical characterization of Cd1-xBexSe and Cd1-xMgxSe crystals

The MOCVD growth of ZnSe using Me2Zn, H2Se and SeEt2

The luminescence properties of ZnSe single crystals doped with isoelectronic substituent Mg by a simple diffusion procedure have been studied It has been shown that Mg easily enters substitutionally on a Zn site forming MgxZn1-xSe mixed crystals with a bandgap energy considerably larger than that of 'pure' ZnSe The photoluminescence spectrum of such crystals is dominated by blue and violet emission, the efficiency of which is much higher than the efficiency of blue luminescence in ZnSe Low-voltage blue-violet electroluminescence with maximum emission at 298 eV at T=45 K and 2875 eV at room temperature in MgxZn1-xSe mixed crystals has been demonstrated, which makes this material very promising for future application in constructing blue and violet light emitting diodes

Luminescence properties of MgxZn1-xSe crystals

MOCVD growth of ZnSe films using diethylselenide

The electroluminescence emission spectrum of forward-biased MIS diodes prepared on high-purity single-crystal ZnSe has been studied over the temperature range 20-290 K. At room temperature the emission consisted of two intense bands in the blue at 4655 and 4770 A, while at the lowest temperatures much more structure was observed. Thus at 20 K free and bound exciton emission was particularly intense, and the donor-acceptor (DA) pair band emission (the Q series), together with its accompanying free-to-bound series was also prominent. The bound exciton, pair band, and free-to-bound emission were all substantially quenched as the temperature was increased, so that at room temperature the two blue bands were the only remaining components of the luminescence. Evidence is produced to demonstrate that the band at 4655 A is associated with free exciton recombination following scattering from free electrons in the conduction band. The band at 4770 A is attributed to free exciton recombination with the emission of two longitudinal optical (LO) phonons.

X.W. Fan

Papers

Blue electroluminescence in forward-biased ZnSe diodes