ABSTRACT High quality ZnS0.06Se0.94 epilayer which was lattice-matched to GaAs substrate has been prepared. The sulfur composition x was 0.06 has been determined by EPMA. The FWHM of X-ray diffraction was 187.2 arcsec. Its R-value was 5.191%. High quality ZnS0.06Se0.94:N epilayer which was lattice-matched to GaAs substrate has been prepared. The FWHM of X-ray diffraction was 169.2 arcsec. Its R-value was 3.521%. ITO film formed by thermal evaporated In-Sn alloy first, then annealing in O2 atmosphere. The conductivity and transparency of ITO have been trade-off at acceptable parameter. Because of the highest current in I-V characteristic in the structure of ITO/ZnS0.06Se0.94:N, we optimized the annealing temperature and time at 450¢J for 60min in O2 atmosphere. Because of the excellent transparency and conductivity in the structure of ITO/Glass, we optimized the annealing temperature and time at 650¢J for 60min in O2 atmosphere. The requirements for an excellent ohmic contact for ZnSe-based blue LED are: (1) transparent (2) low contact resistance (3) good for bonding (4) low melting point. For (1), Tin-doped indium oxide (ITO) is the only good choice. In this study, ITO/ZnS0.06Se0.94:Cl/ZnSe/ZnS0.06Se0.94:N/GaAs:Zn/Au-Zn double heterojunction (DH) structure has been prepared after annealing In-Sn/ZnS0.06Se0.94:Cl/ZnSe/ZnS0.06Se0.94:N/GaAs:Zn/Au-Zn in O2 atmosphere. I-V characteristic of DH junction structure shows a diode electric property.

ABSTRACT ZnSe-based materials have excellent characteristics for blue light emitting devices. So the substrates used for the growth of ZnSe-based alloys are considered from three points of (1) lattice match, (2) thermal match, and (3) interdiffusion. By replacing GaAs or GaP wafers by ZnSe substrates can avoid disadvantages of heteroepitaxy caused by lattice constant mismatch, by differential thermal expansion coefficients between substrate and epilayer. But the ZnSe substrate is cost too much. And it is not easy to achieve. So we choose the other way to get the substrate by Epitaxial Lift-Off (ELO). Another reason for this study is that the light extraction efficiency of these devices is limited by the optically absorbing GaAs substrate. So it can be improved by replacing GaAs with a new metal/glass substrate. The metallic interlayer can be used not only as an adhesive, but also as the reflective mirror to reflect light in the wafer-bonded LED structure. In this study, ZnSe-epliayer have been successfully lifted-off from GaAs by etching solution (NaOH(1M): H2O2(30%) = 4:1 or NH4OH(30%): H2O2(30%) = 9:1) and adhered it onto Indium/glass. From PL spectra, the PL intensity and broad band increases after ELO. The broad band can be decreased by surface trimming of citric etching solution (C6H8O7: H2O: H2O2 = 30g: 30ml: 10ml). This etching process is helpful in regrown ZnSe-epilayer. Regrowth of ZnSSe with [H2Se]/[H2S]¡×4 and II/IV=12.5, shows a NBE emission at 432nm with a FWHM of 26.6 meV at 77K PL spectrum. And the DAP is disappear after regrown. It means that the quality of ZnSe-epilayer becomes better after regrown.