SWITCHING BEHAVIOR IN II-IV-V2 AMORPHOUS-SEMICONDUCTOR SYSTEMS

The electrical characteristics and switching behavior of amorphous ternary semiconducting CdGeAs2 were studied under DC and AC conditions. The samples tested were fabricated as as-quenched bulk compounds, roller splat-quenched ribbons, and Ar-sputtered thin films. Vapor deposited Ag, Au and Al behaved similarly as electrical contacts while the commercial Ag-paste electrodes revealed variable contact resistance. The threshold electric field of ribbon sample was ∼ 5 × 103 V/cm, smaller than ∼ 1.5 × 104 V/cm for the sputtered thin films. The electrical band gap of amorphous CdGeAs2 was determined to be 1.2 eV (n-type). The "forming" process was believed to occur during the first switching cycle whereby highly conductive amorphous channels formed through the width of the samples. The effects of current on switching were investigated and shown not to be significant. The response time for switching decreased approximately exponentially with the applied voltage. The thermal assisted electronic model was postulated for the OFF-ON transition in these materials. © 1990.