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EP-4740712-A1 - INFRARED PHOTODETECTOR AND METHOD FOR PRODUCING AN INFRARED PHOTODETECTOR

EP4740712A1EP 4740712 A1EP4740712 A1EP 4740712A1EP-4740712-A1

Abstract

The invention relates to an infrared photodetector and to a method for producing an infrared photodetector, said infrared photodetector (1) having a silicon element (3), the element having a chalcogen-doped region (9) with a chalcogen concentration of at most 5∙10 19 cm -3 functioning as an infrared-sensitive detection volume.

Inventors

  • Berencén, Yonder
  • Shaikh, Mohd Saif
  • ZHOU, SHENGQIANG

Assignees

  • Helmholtz-Zentrum Dresden - Rossendorf e.V.

Dates

Publication Date
20260513
Application Date
20250508

Claims (10)

  1. 1. Infrared photodetector (1) for detecting infrared radiation, comprising a silicon element (3) with a chalcogen-doped region (9) with a chalcogen concentration of at most 5 10 19 cm -3 .
  2. 2. Infrared photodetector according to claim 1, wherein the chalcogen concentration in the chalcogen-doped region (9) corresponds to a maximum of 5 10 16 cm -3 .
  3. 3. Infrared photodetector according to claim 1 or 2, wherein the silicon element (3) has a p-doped region (7).
  4. 4. Infrared photodetector according to claim 3, wherein the silicon element (3) has an n-doped region (5) in addition to the chalcogen-doped region (9).
  5. 5. Infrared photodetector according to claim 4, wherein the n-doped region (5) is arranged at a distance from the chalcogen-doped region (9) and/or the p-doped region (7) is arranged at a distance from the chalcogen-doped region (9).
  6. 6. Infrared photodetector according to claim 5, wherein the silicon element (3) is undoped in the region between the n-doped region (5) and the chalcogen-doped region (9) and/or in the region between the p-doped region (7) and the chalcogen-doped region (9).
  7. 7. Infrared photodetector according to one of claims 1 to 6, further comprising an insulating layer made of an electrically insulating material, wherein the silicon element is arranged on the insulating layer.
  8. 8. Method for producing an infrared photodetector (1) comprising providing a silicon element (3) and forming a chalcogen-doped region (9) in the silicon element (3) such that the chalcogen-doped region (9) has a chalcogen concentration of at most 5 10 19 cm -3 .
  9. 9. The method of claim 8, wherein the silicon element (3) with the chalcogen-doped region (9) is subjected to a thermal treatment such that the silicon element is heated to a temperature of at least 800°C for a duration of at least 3 seconds. is brought.
  10. 10. The method of claim 9, wherein the duration is at least 5 seconds and/or the temperature is at least 900 °C. The method of claim 9, wherein the duration is at least 5 seconds and/or the temperature is at least 900 °C. ...

Description

Infrared photodetector and method for manufacturing an infrared photodetector TECHNICAL FIELD The present application relates to infrared photodetectors, i.e., photodetectors for detecting infrared radiation. The application also relates to methods for manufacturing infrared photodetectors. BACKGROUND Photodetectors convert received light into an electrical signal. In a semiconductor photodetector, a photon of sufficient energy generates an electron-hole pair in a semiconductor body that is electrically biased by two electrodes. The electric field generated by the two electrodes separates the generated charge carriers according to their polarity. The charge carriers thus generated by photons flow across the electrodes and induce a photocurrent in a load circuit connecting the two electrodes outside the semiconductor body. The photocurrent is a measure of the detected infrared radiation, and, for example, the photocurrent intensity can serve as a measure of the number of detected photons. Infrared photodetectors (abbreviated as "IR photodetectors," where IR is used here and in the following as an abbreviation for "infrared") are photodetectors for detecting infrared radiation. Infrared radiation (IR radiation) is electromagnetic radiation in the wavelength range of approximately 780 nm to 1 mm and in the frequency range of approximately 300 GHz to 400 THz. Infrared photodetectors can be used, in particular, in optical data communication in the so-called O-band in the wavelength range of approximately 1260 nm to 1360 nm and in the so-called C-band in the wavelength range of approximately 1530 nm to 1565 nm. Silicon-based infrared photodetectors are of particular interest in this regard. Silicon-based IR photodetectors can be realized, for example, using chalcogen-doped silicon; see, for example, "Extended infrared photoresponse in Te-hyperdoped Si at room temperature" (M. Wang et al., Phys. Rev. Appl. 10, p. 024054, 2018). Conventionally, such IR photodetectors are based on a silicon substrate into which a chalcogen element (e.g., tellurium) is introduced at a relatively high concentration via ion implantation. In the aforementioned article, tellurium concentrations from 0.25 atomic percent (At%) were investigated, revealing an increase in IR absorption with increasing tellurium concentration. A tellurium concentration above 1 At% or 5 1O 20 cm⁻³ was determined to be suitable for IR photodetection. The chalcogen-doped silicon substrate is conventionally subjected to sub-second thermal treatment by heat-treating it under non-equilibrium conditions, for example, using flash lamp annealing (FLA) in the millisecond range or pulsed laser annealing (PLA) in the nanosecond range. In this process, discontinuous energy input causes local melting and subsequent rapid recrystallization of the chalcogen-doped areas on the irradiated surface of the silicon substrate. The heating remains essentially confined to the near-surface volume of the silicon substrate beneath the irradiated area, and the doping profile of the chalcogen doping is largely preserved even at the high doping concentrations used. Such short-time annealing processes, where the annealing duration is in the sub-second range and the treatment time is a fraction of a second, are also referred to as ultra-short-time annealing processes. The present application aims to provide a cost-effective silicon-based infrared photodetector, particularly for use in the optical telecommunications bands O to U in the wavelength range of 1200 nm to 1700 nm, which enables improved detection of infrared radiation. The application also aims to provide cost-effective and straightforward methods for manufacturing such silicon-based infrared photodetectors. Such infrared photodetectors and methods for manufacturing corresponding infrared photodetectors are provided by the independent claims. Advantageous embodiments are described in the dependent claims. The features and advantages of the disclosed item will become apparent from the following detailed description and the accompanying figures. The elements and structures shown in the schematic figures are not necessarily drawn to scale. Identical reference symbols refer to identical or corresponding elements, structures, and features. BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 shows a schematic cross-section through an infrared photodetector according to one embodiment. Figure 2 shows a flowchart of a method for manufacturing an infrared photodetector according to one embodiment. Figure 3 shows in the upper part a geometry of an infrared photodetector according to an embodiment in a top view and in the lower part a cross-section through a section of the infrared photodetector. Figure 4 shows a doping profile for an n-doped region (Figure 4a), a doping profile for a p-doped region (Figure 4b), and two different doping profiles for a chalcogen-doped region (Figure 4c). Figure 5 shows the dark characteristic curves of infrared photo