InGaAs based long-wavelength near infrared detector arrays are very important for high dynamic
range imaging operations seamlessly from daylight environments to dark environments. These
detector devices are usually made by open-hole diffusion technique which has the advantage of
lower leakage current and higher reliability. The diffusion process is usually done in a sealed
quartz ampoule with dopant compounds like ZnP2, ZnAs3, CdP2 etc. side by side with
semiconductor samples. The ampoule needs to be prepared and sealing process needs to be done
in very clean environment and each time can have variations. In this work we demonstrated
using MOCVD growth chamber to perform the diffusion process. The advantages of such a
process are that the tool is constantly kept in ultra clean environment and can reproducibly
provide clean processes without introducing unexpected defects. We can independently control
the temperature and flow rate of the dopant - they are not linked as in the ampoule diffusion case.
The process can be done on full wafers with good uniformity through substrate rotation, which is
good for large detector array fabrications. We have fabricated different types of InGaAs/InP
detector arrays using dimethyl zinc as the dopant source and PH3 or AsH3 for surface protection.
Pre-studies of Zn-diffusion profiles in InGaAs and InP at different temperatures, flow rates,
diffusion times and followed annealing times were conducted to obtain good control of the
process. Grown samples were measured by C-V profilometer to evaluate the diffusion depth and
doping concentration. The dependence of the diffusion profile with temperature, dopant partial
pressures, and annealing temperature and time and some of the fabricated device characteristics
Miniature robots present a number of challenging problems in controls, as they often exhibit nonlinear dynamics and have strict power and size constraints. These constraints limit the sensing and processing capabilities drastically. Many control techniques require knowledge of the robot’s position, so the position must be estimated when it cannot be sensed directly. We report a mixed signal odometry circuit that maps motor commands to estimated and predicted changes in position in Euclidean space (x, y, θ). We compare the mixed-signal implementation with other approaches and find that the mixed-signal implementation offers significant reductions in power consumption at an acceptable loss of precision.
Cell-based sensors are being developed to harness the specificity and sensitivity of biological systems for sensing
applications, from odor detection to pathogen classification. These integrated systems consist of CMOS chips
containing sensors and circuitry onto which microstructures have been fabricated to transport, contain, and nurture the
cells. The structures for confining the cells are micro-vials that can be opened and closed using polypyrrole bilayer
actuators. The system integration issues and advances involved in the fabrication and operation of the actuators are
PET (Positron Emission Tomography) scanning has become a dominant force in oncology care because of its ability to
identify regions of abnormal function. The current generation of PET scanners is focused on whole-body imaging, and
does not address aspects that might be required by surgeons or other practitioners interested in the function of particular
body parts. We are therefore developing and testing a new class of hand-operated molecular imaging scanners designed
for use with physical examinations and intraoperative visualization. These devices integrate several technological
advances, including (1) nanotechnology-based quantum photodetectors for high performance at low light levels, (2)
continuous position tracking of the detectors so that they form a larger 'virtual detector', and (3) novel reconstruction
algorithms that do not depend on a circular or ring geometry. The first incarnations of this device will be in the form of
a glove with finger-mounted detectors or in a "sash" of detectors that can be draped over the patient. Potential
applications include image-guided biopsy, surgical resection of tumors, assessment of inflammatory conditions, and
early cancer detection. Our first prototype is in development now along with a clinical protocol for pilot testing.
We present the use of electroactive polymer actuators as components of a biolab-on-a-chip, which has potential applications in cell-based sensing. This technology takes full advantage of the properties of polypyrrole actuators as well as the wide range of CMOS sensors that can be created. System integration becomes an important issue when developing real applications of EAP technologies. The requirements of the application and the constraints imposed by the various components must be considered in the context of the whole system, along with any opportunities that present themselves. In this paper, we discuss some of these challenges, including actuator design, the use of complementary actuation techniques, miniaturization, and packaging.