Molecular Beam Epitaxy (MBE) System
The MBE system is the core facility of the Materials Physics Laboratory and has been operational since 2009. The MBE is pumped by a cryopump and has a base pressure of 1.5x10-10 torr. It is equipped with six effusion cells (four standard and two high-temperature), a four-pocket electron beam evaporator, an rf plasma atomic nitrogen source, and an rf plasma atomic oxygen source with high-precision piezoelectric leak valve. The MBE chamber is also outfitted with a differentially-pumped reflection high energy electron diffraction (RHEED) system for real-time in situ monitoring of the growth, and with a quartz crystal microbalance for flux measurement. The system is capable of handling samples from 5 x 5 mm to a 2" wafer. Samples can be heated up to 1000 °C using the oxygen-resistant silicon carbide DCA sample heater. All metal sources and the sample manipulator have pneumatically actuated shutters. The deposition process can be controlled by computer or manually. The system is also equipped with an ethanol-based cryopanel. The ethanol is regulated and recirculated by a Lauda process thermostat.
Transfer Line
The MBE is connected to the other lab facilities by a 12-foot UHV transfer line allowing for the exchange of samples between the STM, XPS/UPS, ALD, and MBE chambers. This in situ sample exchange capability between various systems provides us with a unique capability for complex growth process with characterization at every step of the growth. The transfer line vacuum is maintained by two ion pumps and the transfer mechanism is based on a trolley system. We have the capability of holding up to 20 sample disks in the transfer line using two trolley carts. The trolley cart moves along rails through the entire length of the transfer line using a rack and pinion mechanism. The sample disks can be quickly loaded and unloaded without venting the rest of the transfer line through a load lock located at one end of the transfer line. The load lock is pumped by a turbopump and is also equipped with halogen lamp heaters capable of heating samples to 150 °C for light outgassing prior to moving into the main transfer line. The load lock end of the transfer line is contained within a Class 100 soft wall clean room ensuring a particulate-free sample environment during sample loading. At the opposite end of the transfer line is a high-temperature heating state with gas flow capability for substrate preparation/cleaning as well as post-deposition annealing. The preparation chamber is capable of heating samples up to 1200 °C and is independently pumped by a high throughput turbopump. The preparation chamber is also equipped with a mass spectrometer for temperature-programmed desorption studies.
