Temperature controlled photodetector
View Patent ↗This disclosure describes a temperature controlled photodetector. The disclosed detector can reach a temperature at which responsivity is maximized within a short time and with little wasted power. Furthermore, the photodetector prevents thermal gradients from developing across the detector so that the whole detector region has equivalent responsivity.
1. A temperature controlled photodetector comprising:
a semiconductor substrate having a photosensitive region;
a heating element in contact with the semiconductor substrate;
the semiconductor substrate being thermally isolated from a substrate mount; and
an enclosure comprising a window, attached to the substrate mount, and enclosing the semiconductor substrate and the heating element.
2. The photodetector of claim 1 wherein the heating element has a heating element area larger than a photosensitive area of the photosensitive region.
3. The photodetector of claim 1 wherein a thermally-isolating annular element separates the semiconductor substrate from the substrate mount.
4. The photodetector of claim 1 further comprising at least one electrically conductive lead extending from the heating element through the enclosure and the substrate mount.
5. The photodetector of claim 1 further comprising:
at least one electrically conductive lead extending from the photosensitive region through the enclosure and the substrate mount; and
at least one electrically conductive lead extending from the semiconductor substrate through the enclosure and the substrate mount.
6. The photodetector of claim 1 further comprising a temperature sensor within the enclosure.
7. The photodetector of claim 6 wherein the temperature sensor is in contact with the semiconductor substrate.
8. The photodetector of claim 1 wherein the heating element comprises an electrically-resistive material that generates heat when a current is passed through the electrically-resistive material.
9. The photodetector of claim 1 wherein the enclosure is hermetically sealed.
10. The photodetector of claim 1 wherein the window is optically transparent.
11. A temperature controlled photodetector comprising:
a semiconductor substrate having a photosensitive region;
a heating element in contact with the semiconductor substrate wherein the heating element comprises an electrically-resistive material generating heat when a current is passed through it;
wherein the heating element has a heating element area larger than a photosensitive area of the photosensitive region;
a thermally-isolating annular element in contact with the substrate mount and the semiconductor substrate;
a temperature sensor in contact with the semiconductor substrate;
a hermetically-sealed enclosure comprising a window transparent in the optical and near infrared, attached to the substrate mount, and enclosing the semiconductor substrate, the heating element, the thermally isolating element, and the temperature sensor;
at least one electrically conductive lead extending from the heating element through the enclosure and the substrate mount;
at least one electrically conductive lead extending from the photosensitive region through the enclosure and the substrate mount; and
at least one electrically conductive lead extending from the semiconductor substrate through the enclosure and the substrate mount.
12. The photodetector of claim 1 , wherein the photosensitive region comprises the entire volume of the semiconductor substrate.
13. The photodetector of claim 1 , wherein the photosensitive region comprises a plurality of photosensitive sub-regions.
14. The photodetector of claim 1 , wherein the heating element has a serpentine shape.
15. The photodetector of claim 1 , wherein the window comprises a lens.
16. The photodetector of claim 1 , further comprising a thermally-isolating element.
17. The photodetector of claim 16 , wherein the thermally-isolating element is annular.