Growth and characterization of ZnSe on Si by atomic layer epitaxy

High-quality undoped ZnSe films on n-type (1 0 0)-silicon substrate were ob tained by atomic layer epitaxy (ALE), in which dimethylzinc (DMZn) and hydr ogen selenide (H2Se) were used as the reactants. Key growth steps are descr ibed. Growth parameters were varied to obtain films of higher quality. It w as found that ZnSe monolayer growth rate is independent of substrate temper ature (150-225 degrees C) and the mole fractions of both DMZn and H2Se. ZnS e epilayer characteristics were investigated by XRD, PL and electrical meas urement. A single intense diffraction line was observed at 65.8 degrees, wh ich is slightly smaller than the standard value of bulk ZnSe crystal, confi rming that the epitaxial layer is a (1 0 0)-oriented single-crystalline lay er. PL spectra, obtained at 7 and 300 K, showed a strong and dominant peak emission at near-band-edge emission of 2.81 eV (4412 Angstrom). Schottky di odes were fabricated from the undoped ZnSe layer and the electrical propert ies were measured at room temperature. From the current-voltage (I-V) chara cteristics, a high reverse breakdown voltage (>40 V) and an extremely low c ut-in voltage of 0.6-0.8 V were obtained. On the basis of the observed ZnSe /Si epitaxial film properties, the material is suitable for fabrication of ZnSe-based blue-light-emitting diodes (LEDs) and for application in direct- current thin-film electroluminescence (DCTFEL). (C) 2000 Elsevier Science B .V. All rights reserved.