High-responsivity infrared detector chip structure
The semiconductor structure addresses the trade-off in infrared avalanche devices by separating narrow and wide bandgap layers with a medium bandgap charge control layer, achieving high responsivity and low dark current through reduced tunneling effects.
Patent Information
- Application Number
- CN202510419040.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-04-03
- Publication Date
- 2025-07-15
AI Technical Summary
When traditional infrared avalanche devices improve the built-in electric field to enhance gain, the tunneling effect of narrow bandgap materials leads to a significant increase in dark current, limiting the device's responsiveness and signal-to-noise ratio, making it difficult to achieve a balance between high responsiveness and low dark current.
By separating the narrow bandgap absorption layer and the wide bandgap collision ionization multiplier layer and introducing a medium bandgap charge control layer, the built-in electric field is limited only within the wide bandgap collision ionization multiplier layer, avoiding the electric field extending to the narrow bandgap absorption layer, and achieving a balance between high gain and low dark current.
A high-responsive infrared detector chip structure with low tunneling dark current is achieved, with a gain of more than 100 times and a significant increase in response.
Smart Images
Figure CN120322031A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the field of semiconductor infrared detectors, and specifically to a high responsivity infrared detector chip structure. Background Art
[0002] Infrared detectors are widely used in fields such as astronomical observation, space remote sensing, meteorological detection, and national defense. These fields continuously require detectors to have higher responsivity and lower noise. Avalanche diode devices with internal impact ionization effect gain are a practical choice to improve responsivity.
[0003] When traditional infrared avalanche devices increase the built-in electric field to enhance the gain, due to the tunneling effect of narrow-bandgap materials, the dark current increases significantly, limiting the responsivity and signal-to-noise ratio of the devices. There is a contradiction between the impact ionization multiplication and the tunneling dark current of such devices: in order to finally obtain high responsivity, it is necessary to enhance the impact ionization effect, which requires increasing the magnitude of the built-in electric field. However, increasing the electric field is fatal to long-wave infrared light absorption materials (with a higher tunneling probability for narrow bandgaps). The increase in the built-in electric field will further promote the increase in the tunneling probability of holes (or electrons) inside the material, resulting in a sudden increase in the tunneling dark current. Summary of the Invention
[0004] To solve at least one technical problem in the background art, the present invention provides a high responsivity infrared detector chip structure, which realizes the balance between high gain and low dark current by separating the narrow-bandgap absorption layer from the wide-bandgap impact ionization multiplication layer and introducing a medium-bandgap charge control layer.
[0005] To achieve the above object, the present invention provides a high responsivity infrared detector chip structure, including:
[0006] A narrow-bandgap absorption layer for generating photo-generated carriers through light absorption;
[0007] A medium-bandgap charge control layer located between the narrow-bandgap absorption layer and the wide-bandgap impact ionization multiplication layer, for restricting the built-in electric field only inside the wide-bandgap impact ionization multiplication layer and preventing the electric field from extending to the narrow-bandgap absorption layer;
[0008] A wide-bandgap impact ionization multiplication layer separated from the narrow-bandgap absorption layer, for realizing impact ionization multiplication under high electric fields and amplifying the photocurrent.
[0009] Further, the bandgap width of the narrow-bandgap absorption layer is less than or equal to 0.155 eV, corresponding to long-wave infrared light with a cut-off wavelength greater than or equal to 8 microns.
[0010] Further, the bandgap width of the medium-bandgap charge control layer is greater than or equal to twice the bandgap of the narrow-bandgap absorption layer.
[0011] Further, the bandgap width of the wide bandgap impact ionization multiplication layer is greater than that of the medium bandgap charge control layer.
[0012] Further, the narrow bandgap absorption layer, the medium bandgap charge control layer, and the wide bandgap impact ionization multiplication layer are connected by thin film epitaxial growth.
[0013] Further, the chip structure is applicable to medium-wave, long-wave, and very long-wave high-responsivity infrared detectors.
[0014] The beneficial effects of the present invention are as follows:
[0015] The present invention provides a high-responsivity infrared detector chip structure with low tunneling dark current. By separating the narrow bandgap absorption layer and the wide bandgap impact ionization multiplication layer and introducing a medium bandgap charge control layer, the balance between high gain and low dark current is achieved. Description of the Drawings
[0016] Figure 1 It is a schematic structural diagram of an embodiment of the present invention;
[0017] Figure 2 It is the principle of suppressing the tunneling current of the device in the present invention;
[0018] Figure 3 It is the gain advantage curve of the comparison between the present invention and the traditional design.
[0019] Among them, in the figure: 1 - narrow bandgap absorption layer; 2 - medium bandgap charge control layer; 3 - wide bandgap impact ionization multiplication layer. Specific Embodiments
[0020] The technical solutions in the embodiments of the present invention will be described clearly and completely below. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.
[0021] It should be noted that the terms "first", "second", etc. in the specification and claims of this application and the above-mentioned drawings are used to distinguish similar objects, and do not necessarily need to be used to describe a specific order or sequence. It should be understood that such data can be interchanged under appropriate circumstances so that the embodiments of the present application described here. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or device that includes a series of steps or units does not necessarily have to be limited to those steps or units clearly listed, but may include other steps or units not clearly listed or inherent to these processes, methods, products, or devices.
[0022] In this application, the orientation or positional relationship indicated by terms such as "upper", "lower", "left", "right", "front", "rear", "top", "bottom", "inner", "outer", "middle", "vertical", "horizontal", "lateral", "longitudinal", etc. is based on the orientation or positional relationship shown in the drawings. These terms are mainly used to better describe this application and its embodiments, and are not used to limit that the indicated device, element or component must have a specific orientation, or be constructed and operated in a specific orientation.
[0023] Moreover, in addition to being used to represent the orientation or positional relationship, some of the above terms may also be used to represent other meanings. For example, the term "upper" may also be used to represent a certain attachment relationship or connection relationship in some cases. For those of ordinary skill in the art, the specific meanings of these terms in this application can be understood according to specific circumstances.
[0024] In addition, the terms "mounted", "arranged", "provided with", "connected", "coupled", "socketed" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral structure; it can be a mechanical connection or an electrical connection; it can be directly connected, or indirectly connected through an intermediate medium, or there is internal communication between two devices, elements or components. For those of ordinary skill in the art, the specific meanings of the above terms in this application can be understood according to specific circumstances.
[0025] As Figure 1 shown, the present invention provides a high-response infrared detector chip structure, including:
[0026] A narrow-bandgap absorption layer 1, which is used to generate photo-generated carriers through light absorption; separating the narrow-bandgap absorption layer from the wide-bandgap impact ionization multiplication layer to avoid the contradiction caused by the narrow-bandgap absorption layer and the wide-bandgap impact ionization multiplication layer in the same material in the traditional long-wave infrared detector design, that is, high gain requires a high electric field, while the tunneling dark current of the narrow-bandgap material corresponding to long-wave infrared absorption increases significantly under a high electric field.
[0027] A medium-bandgap charge control layer 2, located between the narrow-bandgap absorption layer and the wide-bandgap impact ionization multiplication layer, which is used to limit the built-in electric field only inside the wide-bandgap impact ionization multiplication layer, avoiding the electric field extending to the narrow-bandgap absorption layer, thereby significantly reducing the tunneling dark current;
[0028] A wide-bandgap impact ionization multiplication layer 3, separated from the narrow-bandgap absorption layer, which is used to achieve impact ionization multiplication under a high electric field and amplify the photocurrent.
[0029] By designing the intermediate-bandgap charge control layer, the electric field within the narrow-bandgap absorption layer is ensured to be close to zero, while the electric field within the wide-bandgap impact ionization multiplication layer is high enough to achieve impact ionization multiplication. The characteristics of the wide-bandgap material significantly increase the upper limit of the electric field within the wide-bandgap impact ionization multiplication layer and simultaneously suppress the tunneling effect.
[0030] Further optimizing the technical solution, the bandgap width of the narrow-bandgap absorption layer 1 is less than or equal to 0.155 eV, corresponding to long-wave infrared light with a cut-off wavelength greater than or equal to 8 microns, preferably 8 to 15 microns.
[0031] Further optimizing the technical solution, the bandgap width of the intermediate-bandgap charge control layer 2 is greater than or equal to twice the bandgap of the narrow-bandgap absorption layer.
[0032] Further optimizing the technical solution, the bandgap width of the wide-bandgap impact ionization multiplication layer 3 is greater than the bandgap width of the intermediate-bandgap charge control layer 2, preferably greater than 0.4 eV.
[0033] Further optimizing the technical solution, the narrow-bandgap absorption layer 1, the intermediate-bandgap charge control layer 2, and the wide-bandgap impact ionization multiplication layer 3 are connected by thin-film epitaxial growth.
[0034] Further optimizing the technical solution, the chip structure is applicable to mid-wave, long-wave, and very long-wave high-responsivity infrared detectors.
[0035] The present invention provides a high-responsivity infrared detector chip structure with low tunneling dark current. By separating the narrow-bandgap absorption layer from the wide-bandgap impact ionization multiplication layer and introducing an intermediate-bandgap charge control layer, a balance between high gain and low dark current is achieved.
[0036] The working principle of the present invention is as follows:
[0037] 1. Long-wave infrared light (with a wavelength between 8 and 15 microns) is incident on the narrow-bandgap absorption layer, generating photo-generated carriers through optical absorption.
[0038] 2. The photo-generated carriers (holes or electrons) enter the wide-bandgap impact ionization multiplication layer through carrier drift and diffusion effects after passing through the intermediate-bandgap charge control layer.
[0039] 3. Within the wide-bandgap impact ionization multiplication layer, the carriers undergo impact ionization under the action of a high electric field, achieving photocurrent amplification and improving the device responsivity.
[0040] 4. Due to the presence of the intermediate-bandgap charge control layer, the built-in electric field is restricted within the wide-bandgap impact ionization multiplication layer, and the electric field within the narrow-bandgap absorption layer is close to zero, thus significantly reducing the tunneling dark current.
[0041] Embodiment
[0042] Reference Figure 1 : From left to right are an N-type doped contact layer for ohmic contact with metal, a long-wavelength infrared InAs / GaSb type-II superlattice narrow-bandgap absorption layer with a cut-off wavelength exceeding 12 μm, a medium-bandgap charge control layer, an AlGaSb impact ionization multiplication layer, and a P-type doped contact layer connected to the ohmic contact on the other side. The medium-bandgap charge control layer is used to confine the built-in electric field only within the multiplication layer. Figure 1 The height of the shown shape reflects the relative magnitudes of the bandgaps between the respective layer structures.
[0043] The long-wavelength infrared InAs / GaSb type-II superlattice narrow-bandgap absorption layer absorbs photons and performs photoelectric conversion. Photo-generated hole carriers obtain current gain in the AlGaSb impact ionization multiplication layer. The gain process generated by electron carriers is similar.
[0044] Figure 2 Demonstrate the principle of suppressing the tunneling current of the device in the present invention. The separated structure design results in that although the reverse bias voltage continuously increases, the high electric field beneficial for gain is still confined within the AlGaSb impact ionization multiplication layer, and the built-in electric field depletion region is blocked outside the long-wavelength infrared InAs / GaSb type-II superlattice narrow-bandgap absorption layer. The bandgap width of the AlGaSb impact ionization multiplication layer ensures that the magnitude of the tunneling current is suppressed to a negligible level. At the same time, the electric field in the long-wavelength infrared InAs / GaSb type-II superlattice narrow-bandgap absorption layer is much lower than the electric field magnitude for generating tunneling current, and the tunneling probability of electrons (holes) therein is close to 0.
[0045] Figure 3 Demonstrate the gain advantage of the present invention compared with the traditional design. In the traditional chip design, since both infrared light absorption and carrier gain occur within the same material, the three contradictions of infrared light absorption (narrow bandgap), high gain (requiring a high electric field), and low tunneling (requiring a low electric field or wide bandgap) coexist. Eventually, it leads to low device gain and small responsivity. The present invention, on the premise of maintaining a low electric field in the long-wavelength infrared light absorption region, uses a wide bandgap to increase the upper limit of the electric field value in the impact ionization gain region and improves the impact ionization ability as much as possible. In contrast, the present invention increases the gain and responsivity of the long-wavelength infrared device by more than 100 times.
[0046] As described above, it is only a preferred embodiment of the present invention, and does not impose any limitation on the technical scope of the present invention. Therefore, any minor modifications, equivalent changes, and decorations made to the above embodiments based on the technical essence of the present invention still fall within the scope of the technical solution of the present invention.
Claims
1. A high-response infrared detector chip structure, characterized in that, Comprising: A narrow bandgap absorption layer (1) for generating photo-generated carriers through light absorption; A medium bandgap charge control layer (2) located between the narrow bandgap absorption layer and the wide bandgap impact ionization multiplication layer, for restricting the built-in electric field only within the wide bandgap impact ionization multiplication layer and preventing the electric field from extending to the narrow bandgap absorption layer; A wide bandgap impact ionization multiplication layer (3) separated from the narrow bandgap absorption layer, for achieving impact ionization multiplication under a high electric field and amplifying the photocurrent.
2. The structure of a highly responsive infrared detector chip as described in claim 1, wherein The bandgap width of the narrow bandgap absorption layer (1) is less than or equal to 0.155 eV, corresponding to long-wave infrared light with a cut-off wavelength greater than or equal to 8 microns.
3. The structure of a highly responsive infrared detector chip according to claim 2, characterized in that, The bandgap width of the medium bandgap charge control layer (2) is greater than or equal to twice the bandgap of the narrow bandgap absorption layer.
4. A high-response infrared detector chip structure according to claim 3, characterized in that, The bandgap width of the wide bandgap impact ionization multiplication layer (3) is greater than the bandgap width of the medium bandgap charge control layer (2).
5. The structure of a highly responsive infrared detector chip as claimed in claim 1, wherein The narrow bandgap absorption layer (1), the medium bandgap charge control layer (2) and the wide bandgap impact ionization multiplication layer (3) are connected by thin film epitaxial growth.
6. The structure of a highly responsive infrared detector chip according to claim 1, characterized in that The chip structure is applicable to mid-wave, long-wave and very long-wave high-responsivity infrared detectors.