Investigation of capillary adhesion between the microcantilever and the substrate with electronic speckle pattern interferometry Appl.

A continuously tunable vertical actuator with subnanometer resolution is presented. It consists of a heterostructure cantilever which has collapsed over a 125 nm thick nanogap. Its operating principle relies on the temperature dependence of the adhesion energy between two InGaAs surface quantum wells. Deflections from −17 to 5 nm with a precision better than three atomic layers have been measured.

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Mechanical positioning is used to control the wavelength of light emission from semiconductor heterostructures. In our work, a Si x N/InP cantilever containing an InGaAs surface well collapses over another InGaAs quantum well. The spacing between the wells varies along the collapsed cantilever, changing the coupling between heterostructures and thus the electron states. In an essence, we are altering the bandgap by the mechanical bending of the cantilever. This is very much similar to the control of photon states by coupling optical cavities with tunable mirrors. Here we report a wavelength shift of up to 22 nm in photoluminescence measurements of two coupled 200 Å surface wells. Associated theory shows that mechanical quantum coupling enables interband or intersubband devices with unprecedented spectral tuning ranges for gain or absorption.