MBE Facilities

MBE group is equipped with state-of-the-art semiconductor deposition, fabrication, and characterization equipment. These facilities are used to grow a wide variety of semiconductor crystals, fabricate devices, and then characterize the quality and properties of the samples or devices.

MOLECULAR BEAM EPITXAY SYSTEMS:
The deposition facility of our group consists of four MBE systems. They are all equipped with RHEED and RGA diagnostics systems, which allow the personnel to monitor crystal growth and residual gas in the chamber while the film is in the process of growing. 

DEP A and DEP B:
Two of our MBE machine, Dep A and Dep B, are VG80H systems. They are specifically dedicated to the growth of conventional compound semiconductor devices.  Dep A grows arsenide-phosphides and Dep B grows arsenide compounds.  Both machines are loaded with Al, In, Ga, Si & Be.  Dep B has an atomic hydrogen source used primarily for removing substrate surface oxide at low temperatures.


Dep A (left) and Dep B (right) for the growth of conventional III-V semiconductor materials - Al, In, Ga, As, P.


DEP C
DepC is an EPI 1040 system.  It has been optimized for the growth of exploratory compound semiconductor materials including arsenic, antimony, and nitrogen.  Gallium, aluminum and indium are introduced through the vaporization of the pure metals in traditional effusion cells.  Boron, silicon and gallium telluride are doping materials.  


DepC is capable of growing semiconductor materials containing Al, In, Ga, As, Sb, and N.

DEP D
Dep D is a heavily modified EPI 930 that has been rotated in three dimensions to have one source port vertically orientated. It was brought on line for the growth of silicon germanium semiconductor materials growth.  Dep D has an atomic hydrogen source, E-beam Si source contained in a small auxiliary chamber, and a solid carbon source for the epitaxial growth of graphene.


Dep D is a heavily modified EPI930 system that grows group IV semiconductor materials.

FABRICATION FACILITIES
The fabrication facilities at LPS are housed in a class 100 clean room.  It is equipped with photo and electron beam lithography systems for pattern generation and transfer, as well as a contact mask aligner.  Both dry and wet chemical etching can be performed using one of three systems.  Rapid temperature annealing is done for metal contacts which are deposited by either resistive heating or electron-beam sources. 

CHARACTERIZATION FACILITES
One of the most important parts of any materials based research facility is characterization. Major characterization methods are used in our group to investigate the growth mechanism, sample quality and device properties of semiconductor materials and devices.

In-situ reflection high energy electron diffraction (RHEED) is employed to monitor the evolution of the substrate surface during growth. Surface morphology of the grown samples is evaluated exsitu by Nomarski microscopy, scanning electron microscopy (SEM) and atomic force microscopy (AFM). The crystalline quality and lattice mismatch are measured by single crystal x-ray diffraction (XRD). Optical properties can be measured by using photoluminescence (PL) at temperatures from 15 K to 300K. A Hall Effects system is used for temperature and magnetic field dependent electrical properties measurements. A Polaron ECV profiler is used to characterize the doping level of materials.