Dr. Malocha’s research group works on acoustoelectronic technology, solid-state devices, and communications systems. The group’s research is focused on surface acoustic wave (SAW) and bulk acoustic wave (BAW) technology, which are used for wireless communication systems, frequency control and sensors. The group works on both theoretical and experimental aspects of device technology, which include materials development and analysis, modeling, fabrication and test and measurement. Communication system models and device integration are also studied.

A new family of gallogermanate compounds having the Ca3Ga2Ge3O14 structure is currently under investigation. A few of these crystals of this family can be grown which include LGS, LGN, LGT, CNGS, CTGS, SNGS and STGS. These new materials have properties that may provide great advantages in BAW and SAW devices used in frequency control technology and sensors. For frequency control applications, the ultimate goal is to find a new material that has high electromechanical coupling and a temperature coefficient of frequency that is zero at room temperature. For sensors, higher operating temperatures and surface transverse waves can open the door to many industrial applications for a range of gas and liquid sensors. These new class of materials have a higher coupling coefficient than quartz, are grown via Czochralski techniques, and can operate at temperatures in excess of 1000 oC.

Research is continuing to determine fundamental material parameters versus temperature, which include the elastic, expansion, piezoelectric and dielectric constants. Given accurate measurement of these constants, predictions of optimum crystal orientations and propagation directions will be obtained. In addition, BAW, SAW, and pseudo-SAW modes can be predicted to exist and can be parameterized.

The acoustoelectronics laboratory has facilities that allow complete material parameter extraction, BAW and SAW device fabrication using cleanroom facilities, device measurement and characterization using a RF probe station, and RF measurement equipment to 6 GHz. Theoretical tools have been developed for wave propagation, materials parameter extraction, device analysis, and device modeling.

Selected Publications
1. Kevin J. Gamble and D C. Malocha, “Simulation of Short LSAW Transducers Including Electrode Mass Loading and Finite Finger Resistance”, IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control, Vol. 49, No. 1, January 2002, pp. 47-56.

2. D.C. Malocha, H. Francois-Saint-Cyr, K. Richardson and R. Helmbold, “ Measurements of LGS, LGN and LGT thermal expansion coefficients of expansion and density”, to be published March 2002, IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control.

3. D.C. Malocha, M.P. da Cunha, E.L. Adler, D. Puccio, and K. Knapp, “Measurements and Predictions of SAW Parameters and Device Performance on LGT-X Substrates”, 2001 IEEE International Frequency Control Symposium, June 2001, pp. 219-222.

4. D.C. Malocha and M.P. da Cunha, “ Sensitivity Analysis for Extraction of Material Constants for Trigonal Crystal Classes”, 2001 IEEE International Frequency Control Symposium, June 2001, pp. 291-295.

5. M.P. da Cunha and D.C. Malocha, “Pure Shear Horizontal Wave on Langatate”, 2000 IEEE Ultrasonic Symposium Proceedings, October 2000, pp. 231-234.

6. M.P. da Cunha and D.C. Malocha, “Experimental and Predicated SAW Temperature Behavior on Langatate”, 2000 IEEE Ultrasonic Symposium Proceedings, October 2000, pp. 245-248.

7. D.C. Malocha, M.P. da Cunha, E. Adler, R.C. Smythe, S. Frederick, M. Chou, R. Helmbold and Y.S. Zhou, “Recent Measurements of Material Constants versus Temperature for Langatate, Langanite and Langasite”, 2000 IEEE International Frequency Control Symposium, June 2000, pp. 200-205.

Simulation results of SAW wave propagation using a time-domain propagation model.

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