Leland Stanford Junior University

Primenano, Inc.

Michael M Kelly

Stuart L Friedman

Zhi-Xun Shen

Zhengyu Wang

Keji Lai

A system for atomic force microscopy in which a sharp electrode tip of an flexing probe cantilever is positioned closely adjacent a sample being probed for its electrical characteristics. An optical beam irradiates a portion of the sample surrounding the probe tips and is modulated at a radio or lower modulation frequency. In one embodiment, a reference microwave signal is incident to the electrode tip. Microwave circuitry receives a microwave signal from the probe tip, which may be the reflection of the incident signal. Electronic circuitry processes the received signal with reference to the modulation frequency to produce one or more demodulated signals indicative of the electronic or atomic properties of the sample. Alternatively, the optical beam is pulsed and the demodulated signal is analyzed for its temporal characteristics. The beam may non-linearly produce the microwave signal. Two source lasers may have optical frequencies differing by the microwave frequency.

Optical source in microwave impedance microscopy

Optically excited microwave impedance microscopy

A microwave microscope including a probe tip electrode vertically positionable over a sample and projecting downwardly from the end of a cantilever. A transmission line connecting the tip electrode to the electronic control system extends along the cantilever and is separated from a ground plane at the bottom of the cantilever by a dielectric layer. The probe tip may be vertically tapped near or at the sample surface at a low frequency and the microwave signal reflected from the tip/sample interaction is demodulated at the low frequency. Alternatively, a low-frequency electrical signal is also a non-linear electrical element associated with the probe tip to non-linearly interact with the applied microwave signal and the reflected non-linear microwave signal is detected at the low frequency. The non-linear element may be semiconductor junction formed near the apex of the probe tip or be an FET formed at the base of a semiconducting tip.

Modulated microwave microscopy and probes used therewith

A microwave imaging microscope and associated probe, or a read head. The probe or the read head includes a sensor unit with three fixed electrodes, preferably a stimulating electrode surrounding a sensing electrode and isolated by a grounded electrode. Circuitry couples the stimulating electrode to the probe signal variably selected in the range of 100 MHz to 100 GHz and couples the sensing electrode to a signal processor detecting in-phase and out-of-phase components of the current or voltage across the sensing electrode and the grounded electrode. A mechanical positioner moves the probe vertically towards the sample and scans it across the sample. The probe may be formed by semiconductor processing methods on a silicon chip.

Growing community of inventors

Portola Valley, CA, United States of America

Michael M Kelly