α‐Ga ₂ O ₃ ‐Based Heterojunction Diodes and Junction Field‐Effect Transistors

This article presents a comprehensive investigation into the suitability of diverse p ‐type materials for the fabrication of pn ‐heterojunctions and junction field‐effect transistors (JFETs) with α‐Ga 2 O 3 . The electrical properties of these materials are examined in detail and compared with one another in order to ascertain their relative merits. Therefore copper iodide (CuI), zinc cobalt oxide (ZCO), and nickel oxide (NiO) are used as p ‐type contacts. The smallest ideality factors are obtained for pn ‐heterojunctions utilizing CuI, whereas the highest current rectification is obtained for diodes with NiO and ZCO contacts, if an oxygen plasma treatment of the α‐Ga 2 O 3 is performed before the deposition of the p ‐type electrode. This way current rectification ratios of up to are achieved. In a next step, these findings are used to fabricate highly functional JFETs with a α‐Ga 2 O 3 channel. These devices exhibit current on/off ratios of up to and small mean sub‐threshold swings of at a low drain voltage of 3 V. High breakdown voltages of up to 418 V are achieved, regardless of the gate material.