Integrated Nanofabrication & Cleanrooms

The Integrated Nanofabrication and Cleanroom Facility (INCF) consists of the III-V and Silicon-based nanofabrication cleanrooms, consolidated into a single facility with expansion in both space and equipment. The cleanroom facility supports research and developments in microfabrication techniques, and device fabrications. Available equipment includes electron microscopy, surface characterization by low energy ion scattering (LEIS),  x-ray photoemission spectroscopy (XPS), nanofabrication, etc. More information is available here.

MOCVD Epitaxy for III-V and III-NITRIDE Semiconductors

Lehigh University’s Smith Family Laboratory supports research in the fields of semiconductor nanostructure, semiconductor optoelectronics, photonics integrated circuits, and III-Nitride and III-V semiconductor devices.

Physics Laser Spectroscopy Laboratory

The laboratory provides various laser sources and optical characterization systems dedicated to spectroscopy and imaging using time- and frequency-resolved laser-based techniques. Available pulsed laser sources range in pulse length from 100 fs to 1 ps and in repetition rate from 80 MHz to 1 kHz, and several continuous wave lasers are also available. In particular, a 1 ps laser source at a repetition rate of 1 kHz can be wavelength-tuned from ~300 nm in the UV to 3 micrometers in the infrared and can also provide pulses in the far infrared up to a 20 micrometers wavelength. Various laser systems are used for pump & probe, transient grating, and four-wave mixing experiments, for studying nonlinear optical effects in fibers, for imaging, and for the investigation of photoluminescence transients on the sub-nanosecond time-scale. A tunable laser source providing 20 ps duration laser pulses at a repetition rate of 10 Hz is also available for time-resolved spectroscopy, or for pump&probe experiments over a time scale of up to 10 ns after excitation.

These laser sources are used in experimental set ups for Maker Fringes (for the determination of nonlinear optical susceptibilities), Degenerate and non-degenerate Four-Wave Mixing, and Laser-induced material shaping, as an example for writing structures through multi- photon absorption and laser heating in the bulk of special glasses and other materials.

The laboratory also has a scanning near-field optical microscope with the possibility of providing localized excitation also at UV wavelengths, and a flexible Olympus microscope with several input and output ports that can be used for laser-based nonlinear optical and multiphoton microscopy, optical tweezing, and luminescence or Raman spectroscopy. A time-correlated single-photon counting system that can be used with repetition rates from 200 kHz to 10 kHz allows the study of fluorescence dynamics from 100 ps after excitation to microseconds after excitation. This allows the study of excited state relaxation also in materials that have long-lived metastable states. Available photoexcitation wavelengths are currently 513 nm and 342 nm.

Experimental Capabilities in Individual Research Groups

Condensed-Matter Spectroscopy

The Condensed Matter Spectroscopy Laboratory under Prof. Stavola studies the role of defects and impurities in semiconductors and semiconductor oxides. The laboratory is a fully equipped facility for making highly sensitive, polarized, infrared absorption measurements of solid-state materials at low temperature. This lab includes a Bomem DA3.16 Fourier Transform Spectrometer that is outfitted with several InSb and MCT detectors for the range 550 to 8500 cm^-1; a custom, liquid-He-cooled, Si bolometer with a cooled filter wheel for the range 200 to 2000 cm^-1; and a Si bolometer for the range 10 to 370 cm^-1 to provide outstanding sensitivity from the far-IR to near-IR. A vacuum interface has been constructed so that an Oxford Instruments CF1204 cryostat can be introduced into the evacuated sample compartment of the Bomem spectrometer. Several continuous-flow, cold-finger cryostats are also available. Absorption measurements can be made from liquid He to room temperature.

While the primary focus of this laboratory has been on impurity vibrations, the broad frequency range of our instrumentation permits far IR studies of the electronic absorption of shallow donor and acceptor impurities and well as the ability to measure accurate free-carrier-absorption spectra providing a contact-free method to measure the conductivity of samples.

Nanoscale Spectroscopy

For the identification and characterization of materials and molecules on the nanoscale, Prof Xu’s Laboratory is maintaining and developing methods and instruments for chemical measurement and imaging at the nanoscale with < 10 nm spatial resolution. Available methods include scattering-type scanning near-field optical microscopy (s-SNOM) and Peak force infrared microscopy.

Transient Absorption and Fluorescence Spectroscopy

The Young Lab has a transient absorption spectrometer that allows to measure photo-physical processes on the femto-to-microsecond timescales. In addition a dedicated fluorometer can be used to measure steady-state or time resolved excitation or emission spectra from both solution and solid-state samples using time-resolved single-photon counting.

Combined Excitation Emission Spectroscopy

The Dierolf lab offers combined excitation emission spectroscopy in spatially resolved confocal or near-field microscopy. This allows for spectroscopical characterization of material systems with high spatial resolution, both under cw-donditions or time-resolved.

Spectrally resolved pump&probe spectroscopy

The Biaggio Lab provides the ability to do pump&probe dynamics on the 1ps to nanosecond time scales using ps pulses that can be wavelength-tuned from the UV to the mid-IR spectral range. This allows for high spectral resolution (about 1 nm bandwidth) and low peak intensities, with a 1 kHz repetition rate, enabling the study of excited state dynamics in samples with a relatively long memory effect. In addition, high sensitivity measurements become possible by doing pump&probe using transient gratings, and can be used in a four-wave mixing geometry to determine third-order nonlinear optical susceptibilities.