RESEARCH


Why is everything wrapped in aluminum foil??


Chamber 1 - Low Temperature-STM
Operated by: Joon and Tobin

The low temperature scanning tunneling microscope (LT-STM) has capabilities from room temperature down to 4.2 K. The LT-STM has dual-purpose scanning tunneling microscopy and scanning tunneling spectroscopy. Additionally, the chamber is equipped with low-energy electron diffraction (LEED), Auger electron spectroscopy (AES), and other equipment such as a sputter gun and a residual gas analyzer. X-ray photoelectron spectroscopy (XPS). The system is intended for the study of the interfaces between Ge and high-k dielectrics. For this purpose there is a differentially pumped dual-use electron beam evaporator / Knudsen cell for deposition of dielectrics from coverages of submonolayer to very thin films (< 1 nm). For studies of surface chemistry during atomic layer deposition (ALD), the system is also equipped with an ALD precursor doser for functionalization of the semiconductor surface. This doser system will also be updated in 2010, including a heated sample stage. Currently, the materials studied in this chamber include Ge(001), hafnium oxide, hafnium, zirconium, oxygen, hydrogen peroxide, water, trimethylaluminum, and tetrakis(ethylmethylamino) zirconium. The ultimate goal of this research is to gain an atomistic and electronic understanding of Ge / high-k systems which can help elucidate guiding physical principles for the development of MOSFET devices with high quality, unpinned semiconductor-oxide interfaces.


Chamber 2 - Variable Temperature-STM/AFM with KPFM
Operated by: Wil and Tyler

The variable temperature is a dual STM and atomic force microscope (AFM) with Kelvin probe force microscopy (KPFM). Microscopy can be done at temperatures up to 500° C. The chamber includes a high temperature effusion cell, e-beam deposition, sputtering, Auger, LEED, and a XPS. Current works include surface studies of InGaAs and high-k oxide deposition of Ga2O and In2O. STS and SKPM are used to determine if Fermi level pinning occurs before and after oxide deposition. For studies of surface chemistry during atomic layer deposition (ALD), the system is also equipped with an ALD precursor doser for functionalization of the semiconductor surface. The dosing system includs a heated sample stage to perform ALD at elevated temperatures. Currently, the materials studied in this chamber include InGaAs(001), InAs(001), GaAs(001), hafnium oxide, hafnium, zirconium, oxygen, hydrogen peroxide, water, trimethylaluminum, diethyl aluminium ethoxide, and tetrakis(ethylmethylamino) zirconium. The ultimate goal of this research is to gain an atomistic and electronic understanding of III-V / high-k systems which can help elucidate guiding physical principles for the development of MOSFET devices with high quality, unpinned semiconductor-oxide interfaces.


Chamber 3
Operated by: Joon Sung

Joon Sung operates the lab's second home-built UHV system. This chamber is equipped with AES, LEED, QMS, and a differentially-pumped rastered-beam ion gun. In addition to these standard tools, it has an in-situ MBE chamber with the capacity to hold up to three high-temperature effusion cells and/or neutral plasma sources, a differentially-pumped molecular beam source chamber equipped with a low-temperature effusion cell, and a STM.

The work currently being performed on this chamber is concerned with the physics and chemistry of the interfaces between the group-IV semiconductor germanium and various potential gate-oxide materials (e.g. GexOy, GeON, GeN, SiO, metal oxides) for the purpose of eventual metal-oxide-semiconductor field effect transistor (MOSFET) fabrication. With the current silicon-based device technology fast approaching insurmountable barriers to further scaling, the scientific community has been fervently working toward some kind of fix (i.e. high-k dielectrics) for, or perhaps even a full replacement of, silicon as the base material in high-tech MOSFET devices. Having similar chemical, physical, and electrical properties as silicon, but possessing higher electron and hole mobilities, we see germanium as being the most feasible and practical candidate, with the potential impressive device characteristics. To this end, we are studying the chemistry of the formation/growth of germanium oxide, nitride, and oxynitride, and the electronic properties of the subsequent interface, with STM/STS and DFT computational modeling.


Chamber 4 - Variable Temperature-STM/AFM with KPFM
Operated by: Jun, Jim, and Erik

We use Scanning Tunneling Microscopy, Atomic Force Microscopy and Kelvin Probe Force Microscopy to investigate the electronic/electrical properties of organic thin films and the effect of various adsorbates on the organic surface. This work complements the OTFT sensor studies by providing fundamental electronic analysis of adsorption properties for vapors interacting with organic thin films. The system is equipped with two in-situ dosing lines for dosing from liquid or vapor sources, a temperature controlled scanning stage (from 50K to 500K), a temperature controlled manipulator (down to 80 K) and an organic effusion cell. Organic thin film growth can be monitored by quartz crystal microbalance. Other preparation and analysis methods include, Low Energy Electron Diffraction (LEED), Auger Electron Spectroscopy (AES), Quadrupole Mass-Spectrometry (QMS), ion sputtering and STM/AFM tip cracking. Present studies involve analysis of oxygen, water and NOx binding to copper phthalocyanine (CuPc), a commonly used material for organic thin film transistors, organic photovoltaics and organic light emitting diodes. Water, oxygen and NOx are well known to alter CuPc device properties however the mechanism of chemical binding and the corresponding changes in electronic structure are poorly understood. Future studies will include in-situ OTFT characterization using the Omicron Mulit-probe connector to operate OTFT sensors in UHV.


ChemFETs
Operated by: Jim

This organic electronics characterization facility is equipped with a Keithley electrometer, a Solartron impedance spectrometer, an SRS lock-in amplifier, an Agilent dynamic signal analyzer, home-built transient spectroscopy, and a custom-built gas flow system. The facility is a very comprehensive setup for organic electronic device characterization and has a unique capability for gas sensor development.

Organic electronics are promising as a complementary technology to inorganic semiconductor devices, as they offer economical processing for low-cost, flexible, and large-area device applications. Despite extensive investigation, a fundamental and comprehensive understanding of charge transport processes in organic thin-film transistors (OTFTs) remains elusive. The ongoing research focuses on electronic properties of trap states that are critical to organic materials. Trap energy distribution, frequency dispersion, and kinetics are under rigorous investigation. Novel readout techniques for gas sensors have been developed based on the fundamental understanding of charge-transport properties.

This research is part of the Integrated Nanosensors AFOSR MURI program. The device fabrication and organic thin film deposition are carried out in the Nano3 clean room and the Integrated Nanosensors Lab, respectively.


Breast Cancer Detection
Maria Jose

The survival for women undergoing breast conservation therapy (BCT) has been shown to be equivalent to mastectomy; for this reason BCT has become the elective surgery treatment for early stage of breast cancer. The main concern of this treatment is the high percentage (20-40%) of these patients that have to undergo a second surgery to remove the rest of the primary tumor. The development of a technique that, intra-operatively assure the absence of tumor cells in the margins of the removed tumor will improve the quality of life of the patients and reduce the cost of the treatment of them.

Our goal is to develop an automated system that can detect the expression of several breast cancer molecular markers and at the same time analyze the morphology of the cells in the margins of the tumor. This information will reduce the number of patients that have to undergo a second surgery and will contribute to a faster and personalized treatment based in the specific characteristics of each tumor.


Research Poster


Last updated: 05/25/2011