Electrical contacts top-type zinc selenide

The electrical properties and structure of three different electrical contacts to p-ZnSe were studied. Sputter deposited Au and Ag contacts were heat treated over a range of 150 to 400{dollar}spcirc{dollar}C to determine the effect of heat treatments on the reverse bias breakdown voltage of these Schottky contacts. The minimum breakdown voltage for Au contacts was found to be {dollar}sim{dollar}3 volts following heat treatment at 350{dollar}spcirc{dollar}C for 30 minutes. Analytical data indicated that Au diffused into the ZnSe during heat treatment, resulting in the formation of deep acceptor levels which led to defect assisted avalanche breakdown dominating conduction. The minimum reverse bias breakdown voltage for Ag contacts was found to be 2.3 volts following heat treatment at 150{dollar}spcirc{dollar}C for 45 minutes. Analytical data indicated that oxygen was incorporated at the Ag/ZnSe interface during deposition and heat treatment which co-doped the surface region of the ZnSe and led to field emission dominating conduction.; The electrical properties and conduction mechanisms of HgSe/p-ZnSe contacts were also studied. These contacts were formed by a novel ex situ process which involved capping the ZnSe with amorphous Se, diffusion of Hg into the Se to form a solid solution, and precipitation of HgSe from solution. Auger, secondary ion mass spectrometry and transmission electron microscopy showed that this process yielded a stoichiometric HgSe layer with regions epitaxed to the underlying ZnSe. Temperature dependant measurements showed that the valence band offset between HgSe and ZnSe was 0.55 eV.; The degradation of ZnTe/ZnSe multiquantum well contacts under high current loading (1000 to 1500 A/cm{dollar}sp2{dollar}) were also studied. Localized temperatures during degradation was measured to be 300{dollar}spcirc{dollar}C or greater at the point where electrical power was supplied. Auger data from degraded samples indicated that due to the localized heating, Zn and Te from the ZnTe layers and Zn from the ZnSe layers diffused through the Au metallization to the sample surface. In addition, thermal stress from the localized heating generated micro-cracks in the ZnSe which acted as high diffusivity paths for impurities. Rectangular defects oriented to the micro-cracks had similar geometries to dislocation patches (dark line defects) which form in the quantum well region of degraded ZnSe based laser devices. This suggests the formation of similar dislocation patches in the quantum well region of the multiquantum well contacts.