Thermally Activated Reversible Threshold Shifts in Yba\u3csub\u3e2\u3c/sub\u3eCu\u3csub\u3e3\u3c/sub\u3eO\u3csub\u3e7-δ\u3c/sub\u3e/Yttria-Stabilized Zirconia/Si Capacitors

Yba2Cu3O7-δ/yttria‐stabilized zirconia (YSZ)/silicon superconductor–insulator–semiconductor capacitors are characterized with capacitance‐voltage (C‐V) measurements at different gate‐voltage sweep rates and under bias‐temperature cycling. It is shown that ionic conduction in YSZ causes both hysteresis and stretch‐out in room‐temperature C‐V curves. A thermally activated process with an activation energy of about 39 meV in YSZ and/or at YSZ/Si interface is attributed to trapping/detrapping mechanisms in the SiOx interfacial layer between YSZ and Si. The negative mobile ions in YSZ can be moved by an applied electric field at room temperature and then ‘‘frozen’’ with decreasing temperature, giving rise to adjustable threshold voltages at low temperatures

Electrical characterization of metal‐insulator‐semiconductor diodes fabricated from laser‐ablated Yba\u3csub\u3e2\u3c/sub\u3eCu\u3csub\u3e3\u3c/sub\u3eO\u3csub\u3e7−δ\u3c/sub\u3e/yttria‐stabilized zirconia films on Si substrates

The purpose of this investigation is to study the electrical properties of the YBCO/YSZ/Si metal‐insulator‐semiconductor structure and the yttria‐stabilized zirconia (YSZ)/Si interface. The YBCO and YSZ layers were epitaxially grown in situ on Si by pulsed laser deposition. Current‐voltage measurements of devices fabricated on p‐type Si(100) showed a small leakage current density at 292 K, which decreased further at 80 K. Comparison of capacitance‐voltage measurements at 292 K for frequencies between 10 and 400 kHz showed a large variation of capacitance in the accumulation region demonstrating the presence of mobile ions in the YSZ layer. This variation is less pronounced at 80 K. A negative shift of about 5 V in threshold voltage from 292 to 80 K has been attributed to redistribution of charges in the YSZ buffer layer

Degradation and Recovery of MOS Devices Stressed with FN Gate Current

Degradation and recovery behaviors of n-channel metal-oxide-semiconductor field-effect transistors (MOSFETs) and MOS capacitors are discussed based on the empirical power law. Devices with different gate oxide thicknesses, 10 and 33 nm, are stressed with Fowler-Nordheim (FN) gate current and the changes in subthreshold swing (S), drain current (ID), transconductance (Gm), threshold voltage (Vh), interface trap density (Dit) above midgap, interface trapped charge (Qit) above midgap, and effective oxide charge (Q0) are measured during and after stressing. All parameters except Vth and Q0 show recovery after degradation. After some stressing conditions, Vth and Q0 show further degradation. It is found that the changes in parameters, during and after stressing, excluding those in Vth and Q0 can be characterized by power laws. The behaviors of Vth and Q0 are more complex, and the change in Vth is found to be influenced by changes in both Q0 and Qit

Fabrication and Electrical Characterization of Superconductor-on- Si Devices

The objectives of this study are to assess the utility of the high‐Tc superconductor, yttrium barium copper oxide (YBCO), as a gate material in two‐ and three‐terminal superconductor‐insulator‐semiconductor (SulS) devices, and to study the electrical properties of the insulator and the insulator/Si interface. The YBCO and yttria‐stabilised‐zirconia (YSZ) layers were epitaxially grown on Si by pulsed‐laser deposition. The SulS diodes were fabricated using standard lithographic techniques, with evaporated gold providing the gate and substrate contacts. Electrical characterisation of these superconducting devices is performed using current vs. voltage and capacitance vs. voltage (C‐V) measurements under bias‐temperature cycling. It is found that deposition of thicker YBCO films (≥ 1500 A) minimises the leakage current of the devices, resulting in electrically stable capacitors, especially at superconducting temperatures. A thermally activated process in the temperature range 80–295 K, as determined from flat‐band shifts of C‐V curves, is attributed to trapping/detrapping mechanisms in the SiOx interfacial layer between YSZ and Si. The mobile ions present in YSZ, which affect the room‐temperature C‐V behaviour, give rise to adjustable threshold voltages at superconducting temperatures. These findings will have a significant impact on future transistors using this capacitor as the gate structure

Effects of Bias-Temperature Cycling on Electrical Characteristics of YBCO/YSZ/Si MIS Capacitors

A bias-temperature cycling technique is developed in the electrical characterization of YBa2Cu307−δ/yttria-stabilized zirconia (YSZ)/Si capacitors. This technique can be used to determine the electrical properties of the material components and their interfaces in the capacitor. Capacitance-voltage (C-V) measurements under no or weak illumination at temperatures ranging from 295 to 80K reveal that hysteresis due to mobile ions decreases with cooling and become vanishingly small at about 220K. Upon further cooling, a different mechanism due to traps in the YSZ/Si interface dominates the low-temperature hysteresis and stretchout of the C-V curves, which is evidenced by measurements for the illuminated device at 80K