Abstract
Fabrication of hydrogen-terminated diamond (H-diamond) field-effect transistor (FET) with AlOx dielectric layer has been successfully carried out. The AlOx layer was formed by auto-oxidizing 6 nm Al film in the air at room temperature, and a FET without AlOx dielectric layer has also been fabricated for comparison. For both FETs, 100 nm Al layers were deposited as the gate electrodes, respectively. The leakage current density in FET with AlOx dielectric layer was four magnitude orders lower than that without AlOx dielectric layer at VGS = −5 V, indicating that AlOx dielectric layer could effectively reduce leakage current and prevent reverse ID in ID − VDS caused by defects on diamond surface. Distinct pinch-off characteristic with p-type channel was observed in ID − VDS measurement. The threshold voltage was −0.4 V at VDS = −15 V.
Highlights
Diamond is an attractive material with many excellent properties such as good bio-compatibility, highest thermal conductivity (22 W/K·cm), large bandgap (5.45 eV), high theoretical breakdown voltage (>10 MV·cm−1), high carrier mobilities etc., having potential applications in biology field, especially electronic devices such as metal oxide semiconductor field-effect transistors (MOSFETs) and metal semiconductor field-effect transistors (MESFETs)[1,2,3,4,5,6,7,8], which can operate in high frequency, high power, high temperature
H-diamond FET with AlOx dielectric layer formed by auto-oxidizing in the air at RT was successfully fabricated
Two 3×3 × 0.5 mm[3] Ib-type single crystal diamonds (001) were used as substrates defined as sample A and B
Summary
Diamond is an attractive material with many excellent properties such as good bio-compatibility, highest thermal conductivity (22 W/K·cm), large bandgap (5.45 eV), high theoretical breakdown voltage (>10 MV·cm−1), high carrier mobilities (electron: 4500 cm[2] V−1 S−1, hole: 3800 cm[2] V−1 S−1) etc., having potential applications in biology field, especially electronic devices such as metal oxide semiconductor field-effect transistors (MOSFETs) and metal semiconductor field-effect transistors (MESFETs)[1,2,3,4,5,6,7,8], which can operate in high frequency, high power, high temperature. In order to overcome this issue, some groups try to use δ-doping technique in diamond. This technique was complex and the carrier mobility is not enough[9,10]. To fabricate gate dielectric layers in H-diamond MOSFETs, many methods have been used such as atomic layer deposition, metal organic chemical vapor deposition or magnetron sputtering techniques. These techniques are expensive, complex and may deteriorate 2DHG channel layer by high temperature or plasma etching, because 2DHG of H-diamond is thermally and chemically instable[18]. To authors’ knowledge, few investigations on H-diamond FETs using autoxidation AlOx dielectric layer has been reported
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