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 including:
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;
testing the device to determine if the device is p-type or n-type;
repeating the implanting, of n-type ions the heating and the testing of the device until the device is n-type; and
forming electrodes electrically connected to the single crystalline n-type Ge layer.
2. The method of claim 1 , wherein the method further includes:
determining whether the device is an n-type device following the heating the device to activate n-type ions in the single crystalline Ge layer; and
implanting additional n-type ions in the single crystalline Ge layer and heating the device to activate the additional n-type ions in the single crystalline Ge layer responsive to determining that the device is not an n-type device.
3. The method of claim 1 , wherein the method further includes removing a portion of the capping insulator layer prior to implanting the n-type ions in the Ge layer.
4. The method of claim 1 , wherein the method further includes forming a germanide material between the electrodes and the single crystalline n-type Ge layer.
5. The method of claim 4 , wherein the germanide material is formed by 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.
6. The method of claim 5 , wherein the layer of metal includes titanium.
7. The method of claim 5 , wherein the device is heated to diffuse the metal at a temperature greater than 300° C.