Li-Chun Chang

Thickness effects on the electrical characteristics of Ba0.7Sr0.3TiO3 capacitors with nano-Cr interlayer

A multilayer Ba0.7Sr0.3TiO3∕Cr∕Ba0.7Sr0.3TiO3 (BST/Cr/BST) structure was sputtered sequentially onto Pt∕Ti∕SiO2∕Si substrate. With the insertion of a 2nm Cr interlayer, the temperature coefficient of capacitance of the BST/Cr/BST dielectric is about 69% lower than that of BST monolayer dielectric. The dielectric constant and dissipation factor as the function of Cr thickness are studied. X-ray diffraction patterns, the analysis results of energy dispersive spectroscopy, and the survey scan profiles of Auger electron spectroscopy reveal the formation of a TiO2 secondary phase after the multilayer is annealed at 800°C in O2 atmosphere. The insertion of nano-Cr interlayer improves the electrical properties of BST capacitors.

Improvement of Electrical Properties of

The metal-insulator-metal (MIM) capacitors were prepared with Ba0.7Sr0.3TiO3/Cr/Ba0.7Sr0.3TiO3 (BST/Cr/BST) dielectric and Pt electrode. The multilayer BST/Cr/BST was sputtered onto Pt/Ti/SiO2/Si substrate. The presence of nano-Cr interlayer affects the electrical properties of the capacitors. The temperature coefficient of capacitance (TCC) of capacitors with 2 nm Cr is about 69% of that of capacitors without Cr. In a previous work, the formation of the TiO2 secondary phase was found after the BST/Cr/BST dielectrics were annealed at 1023 K in O2 atmosphere for 1 h. It is suggested that the nano-Cr interlayer as a catalyst leads to the TiO2 formation during the annealing in O2 atmosphere. The negative value of TCC of BST can be compensated by the positive TCC of TiO2, and the temperature stability in the dielectric constant can be realized for capacitors with nano-Cr interlayer. The voltage stability of BST is also improved with the insertion of nano-Cr interlayer, and the quadratic coefficient in voltage coefficient of capacitance (VCC) of Pt/BST/Cr(2 nm)/BST/Pt is about 30% of that of the BST capacitor without Cr. The effects of Cr thickness on TCC, VCC, dissipation factor, and leakage current density of Pt/BST/Cr/BST/Pt parallel plate capacitors are investigated.The metal-insulator-metal (MIM) capacitors were prepared with Ba0.7Sr0.3TiO3/Cr/Ba0.7Sr0.3TiO3 (BST/Cr/BST) dielectric and Pt electrode. The multilayer BST/Cr/BST was sputtered onto Pt/Ti/SiO2/Si substrate. The presence of nano-Cr interlayer affects the electrical properties of the capacitors. The temperature coefficient of capacitance (TCC) of capacitors with 2 nm Cr is about 69% of that of capacitors without Cr. In a previous work, the formation of the TiO2 secondary phase was found after the BST/Cr/BST dielectrics were annealed at 1023 K in O2 atmosphere for 1 h. It is suggested that the nano-Cr interlayer as a catalyst leads to the TiO2 formation during the annealing in O2 atmosphere. The negative value of TCC of BST can be compensated by the positive TCC of TiO2, and the temperature stability in the dielectric constant can be realized for capacitors with nano-Cr interlayer. The voltage stability of BST is also improved with the insertion of nano-Cr interlayer, and the quadratic coefficient in voltage coefficient of capacitance (VCC) of Pt/BST/Cr(2 nm)/BST/Pt is about 30% of that of the BST capacitor without Cr. The effects of Cr thickness on TCC, VCC, dissipation factor, and leakage current density of Pt/BST/Cr/BST/Pt parallel plate capacitors are investigated.

\hbox{Ba}_{{\bf 0.7}}\hbox{Sr}_{\bf 0.3}\hbox{TiO}_{\bf 3}

The metal-insulator-metal (MIM) capacitors were prepared with Ba0.7Sr0.3TiO3/Cr/Ba0.7Sr0.3TiO3 (BST/Cr/BST) dielectric and Pt electrode. The multilayer BST/Cr/BST was sputtered onto Pt/Ti/SiO2/Si substrate. The presence of nano-Cr interlayer affects the electrical properties of the capacitors. The temperature coefficient of capacitance (TCC) of capacitors with 2 nm Cr is about 69% of that of capacitors without Cr. In a previous work, the formation of the TiO2 secondary phase was found after the BST/Cr/BST dielectrics were annealed at 1023 K in O2 atmosphere for 1 h. It is suggested that the nano-Cr interlayer as a catalyst leads to the TiO2 formation during the annealing in O2 atmosphere. The negative value of TCC of BST can be compensated by the positive TCC of TiO2, and the temperature stability in the dielectric constant can be realized for capacitors with nano-Cr interlayer. The voltage stability of BST is also improved with the insertion of nano-Cr interlayer, and the quadratic coefficient in voltage coefficient of capacitance (VCC) of Pt/BST/Cr(2 nm)/BST/Pt is about 30% of that of the BST capacitor without Cr. The effects of Cr thickness on TCC, VCC, dissipation factor, and leakage current density of Pt/BST/Cr/BST/Pt parallel plate capacitors are investigated.The metal-insulator-metal (MIM) capacitors were prepared with Ba0.7Sr0.3TiO3/Cr/Ba0.7Sr0.3TiO3 (BST/Cr/BST) dielectric and Pt electrode. The multilayer BST/Cr/BST was sputtered onto Pt/Ti/SiO2/Si substrate. The presence of nano-Cr interlayer affects the electrical properties of the capacitors. The temperature coefficient of capacitance (TCC) of capacitors with 2 nm Cr is about 69% of that of capacitors without Cr. In a previous work, the formation of the TiO2 secondary phase was found after the BST/Cr/BST dielectrics were annealed at 1023 K in O2 atmosphere for 1 h. It is suggested that the nano-Cr interlayer as a catalyst leads to the TiO2 formation during the annealing in O2 atmosphere. The negative value of TCC of BST can be compensated by the positive TCC of TiO2, and the temperature stability in the dielectric constant can be realized for capacitors with nano-Cr interlayer. The voltage stability of BST is also improved with the insertion of nano-Cr interlayer, and the quadratic coefficient in voltage coefficient of capacitance (VCC) of Pt/BST/Cr(2 nm)/BST/Pt is about 30% of that of the BST capacitor without Cr. The effects of Cr thickness on TCC, VCC, dissipation factor, and leakage current density of Pt/BST/Cr/BST/Pt parallel plate capacitors are investigated.

Capacitors With an Inserted Nano-Cr Interlayer

Voltage controlled oscillator (VCO) is the most ubiquitous element in all communication systems, wired or wireless. In a wireless system the quality of the communication link is determined in large part by the characteristics of the VCO. The capacitance of metal/insulator/semiconductor (MIS) shows larger variation from the accumulation region to the depletion region. The dielectric constant of hafnium dioxide is larger (around 25) than that of SiO2 (~3.9). Al/Hafnium oxide (HfO2)/Si show a field dependent permittivity and can be used as a dielectric in voltage tunable capacitors. In this work, we used two types of tunable capacitor in the VCO (LC tank and Colpitts circuit) integrated within PCB: one is Al/HfO2/Si (HfO) capacitor, the other one is Philips BB135 p-n junction capacitor for a control. The maximum MIS capacitance ratio is 4.25. The Al/HfO2/Si capacitors are then implemented as the varactor in the VCO circuit.