Richard K Ahrenkiel, Age 61Bradenton, FL

6369603, Apr 9, 2002

Jul 14, 2000

09/615960

Steven W. Johnston - Golden CO
Richard K. Ahrenkiel - Lakewood CO

Midwest Research Institute - Kansas City MO

G01R 3126

324766, 324750

An apparatus for measuring the minority carrier lifetime of a semiconductor sample using radio-frequency coupling. The measuring apparatus includes an antenna that is positioned a coupling distance from a semiconductor sample which is exposed to light pulses from a laser during sampling operations. A signal generator is included to generate high frequency, such as 900 MHz or higher, sinusoidal waveform signals that are split into a reference signal and a sample signal. The sample signal is transmitted into a sample branch circuit where it passes through a tuning capacitor and a coaxial cable prior to reaching the antenna. The antenna is radio-frequency coupled with the adjacent sample and transmits the sample signal, or electromagnetic radiation corresponding to the sample signal, to the sample and receives reflected power or a sample-coupled-photoconductivity signal back. To lower impedance and speed system response, the impedance is controlled by limiting impedance in the coaxial cable and the antenna reactance. In one embodiment, the antenna is a waveguide/aperture hybrid antenna having a central transmission line and an adjacent ground flange.

8581613, Nov 12, 2013

Jan 27, 2010

12/694914

Richard Keith Ahrenkiel - Lakewood CO, US
Donald John Dunlavy - Arvada CO, US

Colorado School of Mines - Golden CO

G01R 31/302

32475431, 32476201, 32475423

A system and method for measuring recombination lifetime of a photoconductor or semiconductor material in real time and without physically contacting the material involving positioning the sample material between a transmitter and a receiver so that electromagnetic signals, preferably radio frequency signals, traveling from the transmitter to the receiver pass through the sample material. The electromagnetic signals are modulated as they pass through the sample material depending on the carrier density and conductivity of the sample material. The modulated electromagnetic signals received by the receiver are then analyzed to determine the carrier recombination lifetime of the sample material.

6275060, Aug 14, 2001

Apr 1, 1999

9/283738

Richard K. Ahrenkiel - Lakewood CO
Steven W. Johnston - Golden CO

Midwest Research Institute - Kansas City MO

G01R 3126

324766

An apparatus for determining the minority carrier lifetime of a semiconductor sample includes a positioner for moving the sample relative to a coil. The coil is connected to a bridge circuit such that the impedance of one arm of the bridge circuit is varied as sample is positioned relative to the coil. The sample is positioned relative to the coil such that any change in the photoconductance of the sample created by illumination of the sample creates a linearly related change in the input impedance of the bridge circuit. In addition, the apparatus is calibrated to work at a fixed frequency so that the apparatus maintains a consistently high sensitivity and high linearity for samples of different sizes, shapes, and material properties. When a light source illuminates the sample, the impedance of the bridge circuit is altered as excess carriers are generated in the sample, thereby producing a measurable signal indicative of the minority carrier lifetimes or recombination rates of the sample.

5541118, Jul 30, 1996

May 22, 1995

8/446466

Dean H. Levi - Lakewood CO
Art J. Nelson - Longmont CO
Richard K. Ahrenkiel - Lakewood CO

Midwest Research Institute - Kansas City MO

H01L 3118

437 4

A process for producing a layer of cadmium sulfide on a cadmium telluride surface to be employed in a photovoltaic device. The process comprises providing a cadmium telluride surface which is exposed to a hydrogen sulfide plasma at an exposure flow rate, an exposure time and an exposure temperature sufficient to permit reaction between the hydrogen sulfide and cadmium telluride to thereby form a cadmium sulfide layer on the cadmium telluride surface and accomplish passivation. In addition to passivation, a heterojunction at the interface of the cadmium sulfide and the cadmium telluride can be formed when the layer of cadmium sulfide formed on the cadmium telluride is of sufficient thickness.

5929652, Jul 27, 1999

Sep 2, 1997

8/922003

Richard K. Ahrenkiel - Lakewood CO

Midwest Research Institute - Kansas City MO

G01R 3126

324766

An apparatus for determining the minority carrier lifetime of a semiconductor sample includes a positioner for moving the sample relative to a coil. The coil is connected to a bridge circuit such that the impedance of one arm of the bridge circuit is varied as sample is positioned relative to the coil. The sample is positioned relative to the coil such that any change in the photoconductance of the sample created by illumination of the sample creates a linearly related change in the input impedance of the bridge circuit. In addition, the apparatus is calibrated to work at a fixed frequency so that the apparatus maintains a consistently high sensitivity and high linearly for samples of different sizes, shapes, and material properties. When a light source illuminates the sample, the impedance of the bridge circuit is altered as excess carriers are generated in the sample, thereby producing a measurable signal indicative of the minority carrier lifetimes or recombination rates of the sample.