| 摘要 |
PURPOSE:To obtain the desired light emitting colors by a method wherein the impurities forming the intermediate energy level are added in the layers with large Eg holding the active layer with small forbidden band width Eg. CONSTITUTION:A transparent electrode 2, a ZnS layer 3 doped with the impurities forming the preferable intermediate energy order, a ZnSe active layer 4, another doped ZnS layer 5 and a backside electrode 6 are laminated on a glass plate 1. At this time, a quantum well QW is formed enclosing electrons and holes in the active layer 4 with small Eg facilitating light emission and recoupling improving the driving voltage. Moreover the quantity of the excited electrons is increased due to the intermediate energy order formed further improving the light emitting efficiency. Besides assuming the thickness of the active layer to be L and the effective mass of the electrons and holes to be me, mh, the substantial Eg equals to the value as follows i.e. Eg=Eg(ZnSe)+h<2>/2me.(pi/L)<2>+ h<2>/2mh.(pi/L)<2>. Thus, all of the intermediate colors of the proper light emitting colors may be produced by means of changing L into Eg (ZnSe)<Eg<Eg(ZnS). |
