Impedance Response and Phase Angle Determination of Metal-Semiconductor Structure with N-Doped Diamond Like Carbon Interlayer
At a Glance
Section titled “At a Glance”| Metadata | Details |
|---|---|
| Publication Date | 2024-01-30 |
| Journal | Gazi University Journal of Science Part A Engineering and Innovation |
| Authors | Nuray Urgun, A. Feizollahi Vahid, Jaafar Alsmael, Barış Avar, Serhat Orkun Tan |
| Institutions | University of Basrah, Bülent Ecevit University |
| Analysis | Full AI Review Included |
Executive Summary
Section titled “Executive Summary”This research investigates the electrical characteristics of a Metal-Interlayer-Semiconductor (MIS) structure utilizing an N-doped Diamond-Like Carbon (N:DLC) thin film as a tunable dielectric interlayer (Al/N:DLC/p-Si/Au).
- Core Achievement: The N:DLC interlayer successfully functions as a high-quality dielectric barrier, enabling the structure to exhibit highly capacitive behavior (phase angle up to 89.89°) in the inversion region.
- Tunability Range: The device demonstrates wide-range electrical tunability, with the complex impedance magnitude (|Z|) shifting dramatically from approximately 1.8 MΩ (low frequency, reverse bias) down to 0.38 kΩ (high frequency, high bias).
- Conduction Mechanism: Phase angle analysis confirms frequency-adjustable working conditions, transitioning from strongly capacitive behavior (inversion) to highly conductive/resistive-like behavior (accumulation).
- Fabrication Method: The structure was fabricated using a hybrid approach combining electrochemical deposition (electrolysis) for the N:DLC layer, RF magnetron sputtering (Au back contact), and thermal evaporation (Al contacts).
- Impedance Behavior: Impedance decreases consistently with rising bias voltage and increasing frequency, proving rising conduction performance across the operational range.
- Application Potential: The demonstrated selective electrical conduction tuning capability suggests the device is suitable for designing frequency-adjustable filter components and enhanced Schottky Barrier Diodes (SBDs).
Technical Specifications
Section titled “Technical Specifications”| Parameter | Value | Unit | Context |
|---|---|---|---|
| Device Structure | Al/N:DLC/p-Si/Au | N/A | Metal-Interlayer-Semiconductor (MIS) |
| Si Substrate Type | Boron-doped p-type | N/A | <100> surface alignment |
| Si Thickness | approx. 300 | µm | Substrate thickness |
| Interfacial Layer Width (di) | 1.0 x 10-6 | m | Constant used for calculations |
| Schottky Contact Area (A) | 0.00785 | cm2 | Calculated area (A = πr2) |
| Applied Bias Range | -3 to +4 | V | Voltage sweep range |
| Frequency Range | 1 to 1000 (1) | kHz (MHz) | Impedance Spectroscopy range |
| Maximum Impedance ( | Z | ) | 1806.25 |
| Minimum Impedance ( | Z | ) | 0.38 |
| Peak Phase Angle (θ) | 89.89 | ° | -3 V, 10 kHz (Highly capacitive) |
| Minimum Phase Angle (θ) | 0.65 | ° | 3.95 V, 1 kHz (Highly resistive/conductive) |
| Vacuum Capacitance (C0) | 6.95 | pF | Calculated value (ε0A/di) |
| Average Phase Angle (Inversion) | 81.36 | ° | Logarithmic frequency values |
Key Methodologies
Section titled “Key Methodologies”The Al/N:DLC/p-Si/Au MIS structure was fabricated using a combination of electrochemical and vacuum deposition techniques, followed by impedance spectroscopy characterization.
- N:DLC Precursor Solution: 100 mL of methanol (CH3OH, 99.5%) and 200 mg of urea were stirred for 15 minutes.
- Electrolysis Setup: A boron-doped p-type Si substrate (<100> alignment) served as the negative electrode, and a graphite plate (4 mm interval) served as the counter electrode.
- N:DLC Deposition: The N:DLC thin film layer was deposited onto the p-Si substrate via electrolysis.
- Back Contact Formation (Au): Au back contact was formed by RF magnetron sputtering at 550 V.
- Annealing: The Au contact was annealed at 550 °C to ensure better ohmic connection.
- Rectifier Contact Formation (Al): High purity Al rectifier contacts were formed via thermal evaporation to complete the Al/N:DLC/p-Si/Au structure.
- Characterization: Impedance spectroscopy measurements were conducted using an HP 4192A LF impedance analyzer across the voltage range (-3 V to +4 V) and frequency range (1 kHz to 1 MHz).
Commercial Applications
Section titled “Commercial Applications”The demonstrated characteristics of the N:DLC MIS structure, particularly its high dielectric quality and tunable impedance response, make it valuable for advanced electronic devices.
- High-Frequency Electronics: Utilizing the fast-switching ability inherent in Schottky Barrier Diodes (SBDs) and the high-frequency response demonstrated up to 1 MHz.
- Tunable Filter Components: The significant, bias-dependent change in capacitance and impedance allows the device to be engineered as a frequency-adjustable filter or band-enhancing component.
- High-Power Multipliers: SBDs are commonly used in high-power frequency multiplier designs, where the robust DLC interlayer can enhance thermal stability.
- Metal-Insulator-Semiconductor (MIS) Devices: Applicable in general MIS technology where high barrier heights, thermal stability, and wear resistance (properties of DLC) are required.
- Sensor Technology: Potential use in devices requiring selective frequency response or voltage-controlled impedance matching.
View Original Abstract
With their superior properties over p-n barriers, Schottky Barrier Diodes have a wide usage area, especially as a test tool to produce better-performance devices. The main performance parameter of these devices is measured by their conduction, which can develop with an interlayer addition through the sandwich design. Regarding the DLC, which also has outstanding specifications under thermal, chemical, and physical conditions, is a good candidate for interlayer tailoring, specifically when used with doping atoms. Thus, this study investigates the impedance response of the fabricated device with an N-doped DLC interlayer by employing the electrochemical technique as a combination of electrolysis, RF magnetron sputtering, and thermal evaporation. The measurements were conducted for broad scales of voltage and frequency corresponding between (-3V) and (+4V) and 1kHz and 1MHz, respectively. According to the impedance analysis, complex impedance decreases by rising bias and frequency, from 1.8 MΩ to 2 k Ω at 1MHZ due to the additional insulating layer. At the same time, the phase angle indicates the quality of the dielectric layer with an average of 81.36 for the sample logarithmic frequency values with an almost constant-like trend in the inversion stage. In comparison, it reduces to an average of 30.25 after the depletion stage by showing the rising conductivity. Moreover, it has some unexpected rising values at the strong accumulation stage, possibly due to the deposited thin film’s unique structure. The supported results by phase angle changes, showing frequency-adjustable working conditions, may offer that selective electrical conduction can be tuned.