Method for producing a multipixel detector
An example includes a method for producing a multipixel detector, the method including: providing a bottom layer including a first and a second bottom electrode, depositing an electrically insulating layer on the bottom layer, forming a first opening through the electrically insulating layer, depositing a first photon absorbing material in the first opening, forming a second opening through the electrically insulating layer, depositing a second photon absorbing material in the second opening, planarizing the deposited electrically insulating layer, the first photon absorbing material, and the second photon absorbing material to form a flat surface, and forming a common top electrode on top of the flat surface.
1 . A method for producing a multipixel detector, the method comprising:
providing a bottom layer comprising a first bottom electrode and a second bottom electrode;
depositing an electrically insulating layer on the bottom layer;
forming a first opening through the electrically insulating layer to the first bottom electrode;
depositing a first photon absorbing material in the first opening to electrically connect to the first bottom electrode;
forming a second opening through the electrically insulating layer to the second bottom electrode;
depositing a second photon absorbing material in the second opening to electrically connect to the second bottom electrode;
planarizing the electrically insulating layer, the first photon absorbing material, and the second photon absorbing material to form a flat surface, wherein the flat surface comprises a top surface of the electrically insulating layer, a top surface of the first photon absorbing material in the first opening, and a top surface of the second photon absorbing material in the second opening separated from the top surface of the first photon absorbing material by the top surface of the electrically insulating layer; and
forming a common top electrode on top of the flat surface, wherein the common top electrode electrically connects to the top surfaces of the first photon absorbing material and the second photon absorbing material on the flat surface,
wherein the common top electrode, the first photon absorbing material in the first opening, and the first bottom electrode form parts of a first thin film photodiode (TFPD), and wherein the common top electrode, the second photon absorbing material in the second opening, and the second bottom electrode form parts of a second TFPD.
2 . The method according to claim 1 , wherein the first TFPD comprises a bottom charge carrier control layer between the first photon absorbing material and the first bottom electrode and a top charge carrier control layer between the first photon absorbing material and the common top electrode.
3 . The method according to claim 2 , wherein the second TFPD comprises the bottom charge carrier control layer between the second photon absorbing material and the second bottom electrode and the top charge carrier control layer between the second photon absorbing material and the common top electrode.
4 . The method according to claim 3 , wherein each of the bottom charge carrier control layer and the top charge carrier control layer comprises an electron transport layer, a hole transport layer, an electron blocking layer, a hole blocking layer, an electron injection layer, or a hole injection layer.
5 . The method according to claim 4 , wherein the method comprises:
depositing the bottom charge carrier control layer in the first opening before depositing the first photon absorbing material in the first opening, such that the first bottom electrode and side walls of the first opening are covered by the bottom charge carrier control layer.
6 . The method according to claim 5 , further comprising depositing the bottom charge carrier control layer in the second opening before depositing the second photon absorbing material in the second opening, such that the second bottom electrode and side walls of the second opening are covered by the bottom charge carrier control layer.
7 . The method according to claim 5 , wherein the method comprises
forming an electrically insulating barrier on the flat surface formed by planarizing the electrically insulating layer, the first photon absorbing material, and the second photon absorbing material, the electrically insulating barrier covering a part of the bottom charge carrier control layer deposited in the first opening or the second opening, wherein the part of the bottom charge carrier control layer lies within the flat surface.
8 . The method according to claim 3 , wherein the method comprises:
providing the bottom charge carrier control layer on the first bottom electrode before depositing the electrically insulating layer.
9 . The method according to claim 8 , further comprising providing the bottom charge carrier control layer on the second bottom electrode before depositing the electrically insulating layer.
10 . The method according to claim 3 , wherein the method comprises:
forming a common top charge carrier control layer configured such that the common top electrode electrically connects to the top surfaces of the first photon absorbing material and the second photon absorbing material in the flat surface via the common top charge carrier control layer, wherein the common top charge carrier control layer is formed after planarizing the electrically insulating layer, the first photon absorbing material, and the second photon absorbing material.
11 . The method according to claim 1 , wherein planarizing the electrically insulating layer, the first photon absorbing material, and the second photon absorbing material comprises chemical-mechanical polishing, grinding, and/or fly-cutting.
12 . The method according to claim 1 , wherein the first photon absorbing material or the second photon absorbing material comprises PbS quantum dots, InAs quantum dots, and/or an organic semiconductor.
13 . The method according to claim 1 , wherein the bottom layer further comprises a complementary metal-oxide-semiconductor, (CMOS) readout integrated circuit, wherein the CMOS readout integrated circuit comprises CMOS electronic circuits configured to convert an amount of charge carriers from the first TFPD and the second TFPD into electrical signals.
14 . The method according to claim 1 , wherein a first absorption peak wavelength of the first photon absorbing material is different from a second absorption peak wavelength of the second photon absorbing material.
15 . The method according to claim 1 , wherein the first bottom electrode is arranged at a first distance from the common top electrode and the second bottom electrode is arranged at a second distance from the common top electrode, wherein the second distance is smaller than the first distance.
16 . The method according to claim 15 , wherein a quantum efficiency of the second photon absorbing material is larger than a quantum efficiency of the first photon absorbing material.
17 . The method according to claim 1 , further comprising:
depositing a sacrificial layer between deposition of the first photon absorbing material and deposition of the second photon absorbing material, such that the first photon absorbing material and the second photon absorbing material are separated by the sacrificial layer,
wherein planarizing the electrically insulating layer comprises removing the sacrificial layer.
18 . The method according to claim 1 , further comprising:
planarizing, in an intermediate planarization step, the electrically insulating layer and the first photon absorbing material, wherein the intermediate planarization step is carried out after depositing the first photon absorbing material in the first opening, and before forming the second opening through the electrically insulating layer.
19 . The method according to claim 1 , wherein
the first opening is formed such that a top part of the first opening is larger than a bottom part of the first opening, whereby the first opening is tapered.
20 . The method according to claim 19 , wherein the second opening is formed such that a top part of the second opening is larger than a bottom part of the second opening, whereby the second opening is tapered.