Germanium photodetector
A method for forming a photodetector device includes forming an insulator layer on a substrate, forming a germanium (Ge) layer on the insulator layer and a portion of the substrate, forming a second insulator layer on the Ge layer, patterning the Ge layer, forming a capping insulator layer on the second insulator layer and a portion of the first insulator layer, heating the device to crystallize the Ge layer resulting in an single crystalline Ge layer, implanting n-type ions in the single crystalline Ge layer, heating the device to activate n-type ions in the single crystalline Ge layer, and forming electrodes electrically connected to the single crystalline n-type Ge layer.
1. A method for forming a photodetector device, the method comprising:
forming a Ge layer on a substrate, wherein holes define a majority carrier of the Ge layer;
forming a first insulator layer on the Ge layer;
implanting n-type ions in the Ge layer;
activating the n-type ions in the Ge layer to form a single crystalline n-type Ge layer
patterning the first insulator layer to expose portions of the single crystalline n-type Ge layer;
forming germanide regions in the exposed portions; and
forming electrodes electrically connected to the germanide regions.
2. The method of claim 1 , wherein patterning the first insulator layer comprises anisotropically etching.
3. The method of claim 1 , wherein forming the germanide regions comprises depositing a layer of metal on an exposed portion of the single crystalline n-type Ge layer and heating the device to diffuse the metal into the single crystalline n-type Ge layer.
4. The method of claim 3 , wherein the metal is selected from the group consisting of titanium, nickel, palladium, platinum, tantalum, copper, tungsten, cobalt, zirconium, and molybdenum.
5. Then method of claim 3 , wherein the metal is titanium.
6. The method of claim 5 , wherein the device is heated to diffuse the metal at a temperature greater than 300° C.
7. The method of claim 1 , wherein the electrodes are formed from titanium, copper or a metallic alloy.
8. The method of claim 1 , wherein the substrate is a single crystalline silicon material.
9. The method of claim 1 , wherein the insulator layer is silicon nitride or silicon oxide.
10. The method of claim 1 , wherein the insulator layer is formed by a low pressure chemical vapor deposition process.
11. The method of claim 1 , wherein the insulator layer is formed by a plasma enhanced chemical vapor deposition process.