John L Little

US Patent:

50478222, Sep 10, 1991

Filed:

Mar 24, 1988

Appl. No.:

7/172518

Inventors:

John W. Little - Wheaton MD
Richard P. Leavitt - Silver Spring MD

Assignee:

Martin Marietta Corporation - Bethesda MD

International Classification:

H01L 2714
H01L 3100

US Classification:

357 30

Abstract:

A quantum well semiconductor device that is responsive to optical energy and operates by resonant field ionization of quantum confined excitons and comprises a semiconductor device including a multi-layered semiconductor structure fabricated on the substrate and including at least two quantum well layers of mutually different widths separated from each other by a semiconductor barrier layer. Because of the different widths, the two quantum well layers have distinct and different electron and hole sub-band energies which when an external electric field is applied across the semiconductor structure, it is possible to bring the electron sub-bands of the wells into resonance, whereupon electrons tunnel back and forth through the barrier layer thereby altering the light absorption coefficient near the excitonic absorption feature. This mechanism provides a means to phase shift or modulate the light traversing through the device.

US Patent:

49489763, Aug 14, 1990

Filed:

Feb 9, 1989

Appl. No.:

7/308409

Inventors:

Shankar B. Baliga - Hauppauge NY
Adishwar L. Jain - Hicksville NY
John A. Little - Northport NY
Martin R. Rost - Islip Terrace NY

Assignee:

Servo Corporation of America - Hicksville NY

International Classification:

H01L 4902
G01J 520

US Classification:

25037006

Abstract:

An infrared detector capable of obtaining coincident fields of view of infrared radiation of different wavelengths is provided. The detector comprises a sandwich-type construction including PbSe and PbS photoconductive film layers.

US Patent:

20190036473, Jan 31, 2019

Filed:

Sep 21, 2017

Appl. No.:

15/710947

Inventors:

- Adelphi MD, US
Andrei V. Sergeyev - Silver Spring MD, US
John W. Little - Ellicott City MD, US

International Classification:

H02S 10/30
H01L 31/054
H01L 31/056
G02B 5/28
G02B 1/115

Abstract:

Embodiments of the invention generally relates to photovoltaic, thermophotovoltaic, and laser power beaming devices which convert solar light, thermal radiation, or laser radiation into electric power. Said devices have a reflective interference “greenhouse” filter placed in front of a semiconductor cell and a reflective mirror on the back of the cell. The front filter is transparent for high energy (short wavelength) photons, but traps low energy (long wavelength) photons emitted by photocarriers accumulated near the semiconductor bandgap. In the optimized PV device, the chemical potential of photoelectrons near semiconductor bandgap exceeds the chemical potential of photoelectrons above the photonic bandgap established by the filter (i.e., the device is in chemical nonequilibrium). The greenhouse filter reduces the emission losses, decreases the semiconductor cell thickness, and provides PV conversion with reduced nonradiative losses. Said device converts radiative energy into electricity in a more efficient way than conventional cells.