Fabrication of Fluoride Resonant Tunneling Diodes on V-Grooved Si(100) Substrates

Abstract

Fluoride resonant tunneling diodes (RTDs) composed of CaF2/CdF2 heterolayers were fabricated in the V-grooved structures surrounded by (111) faces, which were preferred for the growth of the fluoride layers. The structures were formed by anisotropic etching with potassium hydroxide (KOH) or tetramethyl ammonium hydroxide (TMAH) on Si(100) substrates. In the case of KOH etching, RTDs with a high peak to valley current ratio (PVCR) over 105 were obtained. Although the yield of RTDs whose active region was grown directly on the etched surface was very low because of surface roughness, an improved RTD structure, in which the CaxCd1-xF2 separation layer was inserted under the active region, exhibited higher yield. In the case of TMAH etching, the yield was higher than for KOH etching for directly grown RTD structures due to the presence of a smoother etched surface. These results show that the new method proposed in this work is an effective process to fabricate fluoride RTDs on Si(100) substrates.