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KR-20260066196-A - Photodetector including a photonic crystal structure optically coupled to an active layer having enhanced quantum efficiency

KR20260066196AKR 20260066196 AKR20260066196 AKR 20260066196AKR-20260066196-A

Abstract

The present invention relates to a photodetector comprising a support layer (10), a lattice structure (20), and an active layer (30). The lattice structure (20), referred to as a photonic crystal structure, comprises a structured layer (22) consisting of a pattern (22.1) and a continuous sublayer (22.2) of non-zero, constant thickness e ccs , wherein the pattern (22.1) extends along a direction toward the continuous sublayer (22.2). Additionally, the photonic crystal structure (20) has dimensions such that the structured layer (22) forms a photonic crystal that supports at least one guided mode that can be excited by incident light radiation of interest, and the photonic crystal is optically coupled to the active layer (30) such that the guided mode is optically confined within the structured layer (22) and the active layer (30).

Inventors

  • 드루아르, 에마뉘엘
  • 사렐리, 에이리니
  • 세아살, 크리스티앙
  • 우드, 토마
  • 보니, 피에르-이브

Assignees

  • 포토니스 프랑스
  • 썽뜨르 나쇼날르 드 라 르쉐르쉐 씨엉띠삐끄
  • 에꼴 상트랄 드 리옹

Dates

Publication Date
20260512
Application Date
20241024
Priority Date
20231114

Claims (13)

  1. A photodetector (1) configured to detect optical radiation in a predetermined detection spectrum band, comprising a stack, wherein the stack is: A support layer (10) made of a transparent material configured to receive the light radiation at the front (10av) and transmit it through the rear (10ar); A grid structure (20) comprising a pattern (22.1) disposed on the rear surface (10ar) of the support layer (10) and arranged in a main plane parallel to the front surface (10av) of the support layer (10); In the photodetector (1), the photodetector (1) is composed of an active layer (30) made of a semiconductor material that is disposed on the rear surface (20ar) of the above grid structure (20) and is configured to absorb the light radiation: The grid structure (20) comprises a structured layer (22) consisting of the pattern (22.1) and a continuous sublayer (22.2) of a non-zero constant thickness e ccs , wherein the pattern (22.1) has profile widening along a direction toward the support layer (10) and toward the continuous sublayer (22.2); A photodetector (1), wherein the lattice structure (20), referred to as a photonic crystal structure, has dimensions such that the structured layer (22) forms a photonic crystal that supports at least one guided mode that can be excited by incident light radiation of interest, and the photonic crystal is optically coupled to the active layer (30) such that the guided mode is optically confined within the structured layer (22) and the active layer (30).
  2. A photodetector (1), wherein the pattern (22.1) has a height h between its upper portion and base, within a range of 1/10 to 3/4 of the thickness e ccs of the continuous lower layer (22.2) of the structured layer (22).
  3. A photodetector (1), wherein the photonic crystal structure (20) is positioned between the support layer (10) and the structured layer (22) and comprises a so-called filling layer (21) made of a dielectric material having a refractive index n L smaller than the refractive index n H of the structured layer (22) and having a difference n H - n L of at least 0.2.
  4. In claim 3, the photodetector (1) wherein the absolute difference |n L - n cs | between the refractive index n L of the filling layer (21) and the refractive index of the support layer (10) is at most 0.1.
  5. A photodetector (1) according to any one of claims 1 to 4, wherein the refractive index n H of the structured layer (22) has an absolute difference |n H - n ca | from the refractive index of the active layer (30) of at most 0.5.
  6. A photodetector (1), wherein, in any one of claims 1 to 5, the sum of the height h of the pattern (22.1), the thickness e ccs of the continuous sublayer (22.2) of the structured layer (22), and the thickness e ca of the active layer (30) is at least λ r / (2 × <n' H >), where λ r is the wavelength of the waveguide mode and <n' H > is the average refractive index such as the average of the refractive indices of the structured layer (22) and the active layer (30) weighted by their respective thicknesses.
  7. In any one of claims 1 to 6, the pattern (22.1) has a parabolic profile, the photodetector (1).
  8. A photodetector (1) according to any one of claims 1 to 7, wherein the active layer (30) has a rear surface that is in contact with a vacuum opposite to the photonic crystal structure (20).
  9. A photodetector (1), wherein, in any one of claims 1 to 8 and claim 3, the filling layer (21) is made of oxide.
  10. In claim 9, the photodetector (1), wherein the filling layer (21) is made of silicon oxide.
  11. A photodetector (1), wherein, in any one of claims 1 to 10, the active layer (30) is a photoemissive layer made of a material based on SbNaKCs, SbNa2KCs , SbNaK, SbKCs, SbRbKCs or SbRbCs or a material based on AgOCs.
  12. In any one of claims 1 to 11, the photodetector (1) is an image intensifier tube or a photomultiplier tube.
  13. A method for manufacturing a photodetector (1) as described in any one of claims 1 to 12, A step of forming a stack consisting of a thick layer (40), a so-called filling layer (21), and an upper thin film (41); A step of forming through openings (43) in the upper thin film (41) that emerge onto the filling layer (21) and are regularly arranged at a pitch p of the pattern (22.1); A step of partially isotropic wet etching of the filling layer (21) at the through opening (43) to form periodic etching regions (44) for forming the above pattern (22.1); and then removing the upper thin film (41); A step of depositing a layer (22) forming the structured layer above onto the filling layer (21); A step of depositing the active layer (30) on the structured layer (22); A method for manufacturing a photodetector (1), comprising the step of removing the thick layer (40) and assembling the support layer (10) on the exposed surface of the filling layer (21).

Description

Photodetector including a photonic crystal structure optically coupled to an active layer having enhanced quantum efficiency The present invention relates to a photodetector, for example, an array photodetector comprising a grating structure and an active layer configured to absorb light radiation to be detected. A photodetector of electromagnetic radiation receives and detects electromagnetic radiation by converting it into an output light emission or electrical signal, such as an output signal consisting of charge carriers photogenerated in an active layer, for example. Document WO2014/056550 describes an example of an electron radiation photodetector, such as an image intensifier tube or a photomultiplier tube. As illustrated in FIG. 1, the photodetector (A1) comprises an inlet window (A10) that is transparent to the radiation to be detected and an active photoemissive layer (A30) disposed on the back of the inlet window (A10). The latter is configured to receive incident electromagnetic radiation and transmit a photoelectron flux in response thereto. An output device (not shown) receives the photoelectron and generates an output signal in response after multiplying the photoelectron by a secondary electron flux. The quantum efficiency of the active layer (A30) corresponds to the ratio of the number of emitted photoelectrons to the number of incident photons received. This depends particularly on the incident photon absorption rate, the photoelectron transfer rate to the light-emitting surface (back side of the active layer), and the photoelectron emission rate to the outside of the active layer (A30). The absorption rate and transmission rate show opposite trends depending on the thickness of the active layer (A30); that is, the absorption rate increases as the thickness increases, while the transmission rate decreases, so there exists an optimal thickness that can maximize the product of these two rates. However, the absorption rate was found to decrease sharply, especially at a high wavelength of about 800 nm. To improve the performance of the photodetector (A1), increasing the thickness of the active layer (A30) to increase the absorption rate is a natural solution, but as previously discussed, this will result in a decrease in the transmission rate. Additionally, the photodetector (A1) includes a grating structure (A20) that forms a transmission diffraction grating located between the inlet window (A10) and the active layer (A30). Incident photons transmitted by this diffraction grating penetrate into the active layer (A30) with a non-zero diffraction angle with respect to the front normal of the active layer (A30). Consequently, the apparent thickness of the active layer (A30) recognized by the photons becomes thicker, thereby improving the absorption rate without reducing the transmittance. Thus, the quantum efficiency of the active layer (A30) is improved. However, it is necessary to improve the performance of such photodetectors, and furthermore, any photodetector composed of a transparent support layer, a lattice structure, and an absorption active layer. To this end, the object of the present invention is a photodetector comprising a transparent support layer, a lattice structure (photonic crystal structure), and an absorption active layer, wherein the photodetector has enhanced performance, particularly due to an increase in the quantum efficiency of the active layer. To this end, the object of the present invention is a photodetector configured to detect optical radiation in a predetermined detection spectrum band, comprising a stack, wherein the stack comprises: A support layer made of a transparent material configured to receive optical radiation from the front and transmit it through the rear; A grid structure disposed on the rear surface of a support layer and comprising a pattern disposed in a main plane parallel to the front surface of the support layer; It consists of an active layer made of a semiconductor material positioned on the back surface of a lattice structure to absorb light radiation. According to the present invention, the grid structure comprises a structured layer consisting of the pattern and a continuous sublayer with a non-zero constant thickness e ccs , and the pattern has profile widening along the direction toward the support layer and toward the continuous sublayer. In addition, a lattice structure referred to as a photonic crystal structure has dimensions such that the structured layer forms a photonic crystal that supports at least one guided mode that can be excited by incident light radiation of interest, and the photonic crystal is optically coupled to the active layer such that the guided mode is optically confined within the structured layer and the active layer. Specific, desirable but non-limiting, embodiments of this photodetector are as follows. The pattern may have a height h between its top and base, within a range of 1/10 to 3/4 of the thickness e cc