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Evaluation of intrinsic charge carrier transport at insulator-semiconductor interfaces probed by a non-contact microwave-based technique.

Honsho Y, Miyakai T, Sakurai T, Saeki A, Seki S - Sci Rep (2013)

Bottom Line: We have successfully designed the geometry of the microwave cavity and the thin metal electrode, achieving resonance of the microwave cavity with the metal-insulator-semiconductor (MIS) device structure.By means of the present measurement system named field-induced time-resolved microwave conductivity (FI-TRMC), the pentacene thin film in the MIS device allowed the evaluation of the hole and electron mobility at the insulator-semiconductor interface of 6.3 and 0.34 cm² V⁻¹ s⁻¹, respectively.This is the first report on the direct, intrinsic, non-contact measurement of charge carrier mobility at interfaces that has been fully experimentally verified.

View Article: PubMed Central - PubMed

Affiliation: Department of Applied Chemistry, Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871, Japan.

ABSTRACT
We have successfully designed the geometry of the microwave cavity and the thin metal electrode, achieving resonance of the microwave cavity with the metal-insulator-semiconductor (MIS) device structure. This very simple MIS device operates in the cavity, where charge carriers are injected quantitatively by an applied bias at the insulator-semiconductor interface. The local motion of the charge carriers was clearly probed through the applied external microwave field, also giving the quantitative responses to the injected charge carrier density and charge/discharge characteristics. By means of the present measurement system named field-induced time-resolved microwave conductivity (FI-TRMC), the pentacene thin film in the MIS device allowed the evaluation of the hole and electron mobility at the insulator-semiconductor interface of 6.3 and 0.34 cm² V⁻¹ s⁻¹, respectively. This is the first report on the direct, intrinsic, non-contact measurement of charge carrier mobility at interfaces that has been fully experimentally verified.

No MeSH data available.


Schematic drawing of the FI-TRMC measurement system.The microwave circuit was designed for X-band microwaves (~9 GHz).
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f3: Schematic drawing of the FI-TRMC measurement system.The microwave circuit was designed for X-band microwaves (~9 GHz).

Mentions: For the first demonstration of FI-TRMC, we prepared a metal-insulator-semiconductor (MIS) device adopting a Au/SiO2/PMMA/pentacene/Au configuration (Fig. 2). We used pentacene as a representative organic semiconductor with high hole mobility2526, while PMMA was selected as an insulator. Two gold electrodes working as a gate enable control of the density and polarity of the accumulated charge carriers at the interfaces by applying a gate bias voltage, which leads to the direct quantification of the charge carrier numbers. Equation (1) shows the relationship between the change in charge carrier number (ΔN) and the change in the applied gate bias voltage (ΔV). where C and e show the capacitance and the elementary charge of an electron, respectively. The value of N was determined by a Wayne Kerr Precision Component Analyzer 6430B capacitive sensor. Through atomic force microscopy (AFM), the vapor-deposited pentacene film in the MIS device (Fig. 2d) was characterized as having a typical polycrystalline morphology (Supplementary Fig. S1). In addition, an FET-type device with a configuration analogous to the MIS device (Fig. S2) exhibited typical FET characteristics (Fig. S3). These observations indicated that the MIS device is appropriately designed for FI-TRMC measurements. Fig. 3 shows a schematic illustration of a microwave circuit for FI-TRMC using X-band microwave radiation (~9 GHz). In FI-TRMC measurements, the microwave frequency and power are adjusted by a Rohde Schwarz SMF 100 A Signal Generator at ~ 9.0 GHz and 0.9–1.0 mW, respectively. The motion of charge carriers accumulated at the interfaces is modulated by the low electric field associated with the microwaves. Holes or electrons are directly injected by application of a microsecond-pulse bias voltage from a Wave Factory Multifunction Generator WF 1973, promoting field-induced charge-carrier generation at the pentacene–PMMA interface. The FI-TRMC signals picked up by a diode (rise time < 1 ns) were monitored by a Tektronix TDS5054 Digital Phosphor Oscilloscope. All the experiments were carried out under ambient atmosphere at room temperature.


Evaluation of intrinsic charge carrier transport at insulator-semiconductor interfaces probed by a non-contact microwave-based technique.

Honsho Y, Miyakai T, Sakurai T, Saeki A, Seki S - Sci Rep (2013)

Schematic drawing of the FI-TRMC measurement system.The microwave circuit was designed for X-band microwaves (~9 GHz).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3822380&req=5

f3: Schematic drawing of the FI-TRMC measurement system.The microwave circuit was designed for X-band microwaves (~9 GHz).
Mentions: For the first demonstration of FI-TRMC, we prepared a metal-insulator-semiconductor (MIS) device adopting a Au/SiO2/PMMA/pentacene/Au configuration (Fig. 2). We used pentacene as a representative organic semiconductor with high hole mobility2526, while PMMA was selected as an insulator. Two gold electrodes working as a gate enable control of the density and polarity of the accumulated charge carriers at the interfaces by applying a gate bias voltage, which leads to the direct quantification of the charge carrier numbers. Equation (1) shows the relationship between the change in charge carrier number (ΔN) and the change in the applied gate bias voltage (ΔV). where C and e show the capacitance and the elementary charge of an electron, respectively. The value of N was determined by a Wayne Kerr Precision Component Analyzer 6430B capacitive sensor. Through atomic force microscopy (AFM), the vapor-deposited pentacene film in the MIS device (Fig. 2d) was characterized as having a typical polycrystalline morphology (Supplementary Fig. S1). In addition, an FET-type device with a configuration analogous to the MIS device (Fig. S2) exhibited typical FET characteristics (Fig. S3). These observations indicated that the MIS device is appropriately designed for FI-TRMC measurements. Fig. 3 shows a schematic illustration of a microwave circuit for FI-TRMC using X-band microwave radiation (~9 GHz). In FI-TRMC measurements, the microwave frequency and power are adjusted by a Rohde Schwarz SMF 100 A Signal Generator at ~ 9.0 GHz and 0.9–1.0 mW, respectively. The motion of charge carriers accumulated at the interfaces is modulated by the low electric field associated with the microwaves. Holes or electrons are directly injected by application of a microsecond-pulse bias voltage from a Wave Factory Multifunction Generator WF 1973, promoting field-induced charge-carrier generation at the pentacene–PMMA interface. The FI-TRMC signals picked up by a diode (rise time < 1 ns) were monitored by a Tektronix TDS5054 Digital Phosphor Oscilloscope. All the experiments were carried out under ambient atmosphere at room temperature.

Bottom Line: We have successfully designed the geometry of the microwave cavity and the thin metal electrode, achieving resonance of the microwave cavity with the metal-insulator-semiconductor (MIS) device structure.By means of the present measurement system named field-induced time-resolved microwave conductivity (FI-TRMC), the pentacene thin film in the MIS device allowed the evaluation of the hole and electron mobility at the insulator-semiconductor interface of 6.3 and 0.34 cm² V⁻¹ s⁻¹, respectively.This is the first report on the direct, intrinsic, non-contact measurement of charge carrier mobility at interfaces that has been fully experimentally verified.

View Article: PubMed Central - PubMed

Affiliation: Department of Applied Chemistry, Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871, Japan.

ABSTRACT
We have successfully designed the geometry of the microwave cavity and the thin metal electrode, achieving resonance of the microwave cavity with the metal-insulator-semiconductor (MIS) device structure. This very simple MIS device operates in the cavity, where charge carriers are injected quantitatively by an applied bias at the insulator-semiconductor interface. The local motion of the charge carriers was clearly probed through the applied external microwave field, also giving the quantitative responses to the injected charge carrier density and charge/discharge characteristics. By means of the present measurement system named field-induced time-resolved microwave conductivity (FI-TRMC), the pentacene thin film in the MIS device allowed the evaluation of the hole and electron mobility at the insulator-semiconductor interface of 6.3 and 0.34 cm² V⁻¹ s⁻¹, respectively. This is the first report on the direct, intrinsic, non-contact measurement of charge carrier mobility at interfaces that has been fully experimentally verified.

No MeSH data available.