Atomic force microscopy apparatus, methods, and applications
AssigneeCornell University
InventorsJohn Marohn, Sarah Nathan, Ryan Dwyer
Life of this patent
Estimating the term…
Abstract
Atomic force microscopy apparatus and method that enable observing charge generation transients with nanometer spatial resolution and nanosecond to picosecond time resolution, the timescale relevant for studying photo-generated charges in the world's highest efficiency photovoltaic films. The AFM apparatus includes an AFM, a light source for illumination of a sample operatively coupled to the AFM, a voltage source operatively coupled to the AFM, and a control circuitry operatively coupled to the light source and the voltage source. The AFM apparatus improves the time resolution and enables rapid acquisition of photocapacitance transients in a wide array of solar-energy-harvesting materials.
Claims16
A method for measuring the time-evolution of charge or polarization induced by light in a sample, comprising the steps of:
- providing an atomic force microscope (AFM) in operating condition including a light source for illumination of a sample, and further including a voltage source;
- obtaining a reference measurement of at least one of an amplitude, a frequency, and a phase of a cantilever of the operating AFM;
- applying, with the voltage source, a ΔV pulse between the cantilever and the sample, and illuminating the sample with a light pulse from the light source;
- determining at least one of a change in the cantilever amplitude or phase by measuring the amplitude or phase after the ΔV pulse;
- and
- determining the time-evolution of charge or polarization based at least in part on a determined change in the cantilever amplitude or phase, wherein the change in cantilever amplitude or phase is a function of a duration of the ΔV pulse, a duration of the light pulse, or a relative time delay between two or more ΔV pulses or two or more light pulses.
A method for measuring the time-evolution of charge or polarization induced by light in a sample, comprising the steps of:
- providing an atomic force microscope (AFM) in operating condition including a light source for illumination of a sample, and further including a voltage source;
- obtaining a reference measurement of at least one of an amplitude, a frequency, and a phase of a cantilever of the operating AFM;
- applying, with the voltage source, a ΔV pulse between the cantilever and the sample and illuminating the sample with a light pulse from the light source, wherein the light source comprises a first laser configured to emit light pulses at a tip of the cantilever, and further comprises a second laser configured to emit light pulses at the tip of the cantilever;
- and
- determining at least one of a change in the cantilever amplitude or phase versus:
- (i) a duration of the ΔV pulse, (ii) a duration of the light pulse, or (iii) a relative time delay between two or more ΔV pulses or two or more light pulses.
A method for measuring the time-evolution of charge or polarization induced by light in a sample, comprising the steps of:
- providing an atomic force microscope (AFM) in operating condition including a light source for illumination of a sample, and further including a voltage source;
- obtaining a reference measurement of at least one of an amplitude, a frequency, and a phase of a cantilever of the operating AFM;
- applying, with the voltage source, a ΔV pulse between the cantilever and the sample and illuminating the sample with a light pulse from the light source;
- determining at least one of a change in the cantilever amplitude or phase versus:
- (i) a duration of the ΔV pulse, (ii) a duration of the light pulse, or (iii) a relative time delay between two or more ΔV pulses or two or more light pulses;
- and
- deriving a photocapacitance measurement of the sample from the determined at least one of a change in the cantilever amplitude or phase versus a duration of the ΔV pulse, a duration of the light pulse, or a relative time delay between two or more ΔV pulses or two or more light pulses.
Dependencies are inferred from the claim text.