EP2054705A1

EP2054705A1 - Radiation detector with an adjustable spectral sensitivity

Info

Publication number: EP2054705A1
Application number: EP07847523A
Authority: EP
Inventors: Arndt Jaeger; Peter Stauss; Klaus Streubel; Werner Kuhlmann
Original assignee: Osram Opto Semiconductors GmbH
Current assignee: Ams Osram International GmbH
Priority date: 2006-11-30
Filing date: 2007-11-29
Publication date: 2009-05-06
Also published as: WO2008065170A1; TW200844412A; US8274657B2; JP2010511162A; KR20090098850A; TWI365976B; CN101535785A; DE102007012115A1; KR101430030B1; CN101535785B; US20100097609A1

Abstract

The invention specifies a radiation detector (1) having a detector arrangement (2), which has a plurality of detector elements (4, 5, 6) which are used to obtain a detector signal (DS) during operation of the radiation detector, and having a control apparatus (3), wherein the detector elements each have a spectral sensitivity distribution (400, 500, 600) and are suitable for generating signals (S4, S5, S6), at least one detector element contains a compound semiconductor material and this detector element is designed to detect radiation in the visible spectral range, the radiation detector is designed in such a manner that the sensitivity distributions of the detector elements are used to form different spectral sensitivity channels (420, 520, 620) of the radiation detector, a channel signal (K4, K5, K6) which is assigned to the respective sensitivity channel can be generated in the sensitivity channels using the detector elements, and the control apparatus is designed in such a manner that the contributions of different channel signals to the detector signal of the radiation detector are controlled differently.

Description

description

RADIATION DETECTOR WITH ADJUSTABLE SPECTRAL SENSITIVITY

The present invention relates to a radiation detector.

An object of the present invention is to provide a radiation detector which can be used variably.

This object is achieved by a radiation detector having the features of patent claim 1. Advantageous embodiments and further developments are the subject of the dependent claims.

A radiation detector according to the invention comprises a detector arrangement which has a plurality of detector elements, by means of which a detector signal is obtained during operation of the radiation detector. Furthermore, the radiation detector has a control device. The detector elements each have a spectral sensitivity distribution and are suitable for signal generation. At least one detector element contains a compound semiconductor material and this detector element is designed to detect radiation in the visible spectral range. Furthermore, the radiation detector is designed such that by means of the sensitivity distributions of the detector elements different spectral

Sensitivity channels of the radiation detector are formed. In the sensitivity channels, a channel signal associated with the respective sensitivity channel can be generated by means of the detector elements. The

Control device is further designed such that the contributions of different channel signals to the detector signal the radiation detector are regulated differently and preferably regulated differently.

The control device is suitably electrically connected to the detector arrangement. Signals generated in the detector arrangement can thus be fed to the control device in a simplified manner.

Compound semiconductor materials are particularly suitable for the detection of radiation in the visible spectral range. In particular, this is compared to the

Element semiconductor material to see silicon. Silicon has a particularly high sensitivity in the infrared spectral range. In the event that silicon is to be used for the detection of visible radiation, the infrared radiation component from the radiation incident on the detector must be elaborately filtered out by external filters in order to prevent infrared radiation components from contributing to the detector signal.

If, in contrast, a compound semiconductor material is used for detection, then the compound semiconductor material can be chosen in a simplified manner such that it is comparatively insensitive in the infrared spectral range. The use of complex external filters for long-wave infrared radiation can thus be avoided. On the one hand so the space requirement and on the other hand, the manufacturing cost is reduced because external filters such. B. interference filter, the total cost of the radiation detector can increase significantly.

III-V compound semiconductor materials are for the detection of visible radiation, for example with wavelengths between Including 420 nm and 700 nm inclusive, particularly suitable because they can have particularly high efficiencies in the visible spectral range. Of the III-V compound semiconductor materials is a compound semiconductor material of the material system In _y Al _x Gai- _x -y P with 0 ≤ x ≤ 1 and 0 ≤ y ≤ 1, preferably with x ≠ 0, y ≠ 0, x ≠ 1 and / or y ≠ 1 especially. By means of a compound semiconductor material from the material system (In, Al, Ga) P, radiation can be detected over the entire visible spectral range. About the composition and in particular the choice of Al content, the band gap of a layer can be adjusted from this material system. Since InGaAlP is not significantly sensitive in the infrared spectral range, a long-wave cut-off wavelength, in particular a cut-off wavelength in the visible spectral range, of the spectral sensitivity distribution of the respective detector element can already be set via the band gap. External filters are not required for this.

The spectral sensitivity distribution of a detector element is determined by dependence of the strength of the signal generated in the respective detector element - z. As the photocurrent or dependent thereon sizes - determined by the wavelength of the incident radiation to this detector element.

By means of the control device, a predetermined spectral distribution of the detector sensitivity, ie the spectral sensitivity distribution of the entire radiation detector, can be set. The

Sensitivity distribution of the entire radiation detector results, for example, from the dependence of one Output signal of the radiation detector, which can be obtained after passing through the control device, of the wavelength of the incident radiation. By means of different regulation of the contributions of different channel signals to the total detector signal, a predetermined sensitivity distribution of the radiation detector can therefore be set via the control device.

Preferably, the relative weighting of contributions of different channel signals to the detector signal of the radiation detector is regulated by means of the control device. In particular, the control device may weight contributions from channel signals to the detector signal relative to each other differently. Due to the different weighting of the contributions of channel signals to the entire detector signal, the predetermined sensitivity distribution of the radiation detector can be adjusted. In this case, the respective channel signals or the corresponding spectral distributions of the sensitivity channels can be selectively attenuated or amplified by means of the control device.

Subsequently, the differently weighted channel signals can be superimposed so that the detector signal behaves according to the predetermined distribution of the detector sensitivity. The detector signal of the radiation detector can be formed in particular by means of superposition, for example by means of addition, of channel signals, which are preferably weighted differently. A plurality of channel signals may contribute to the detector signal of the radiation detector. Preferably, the channel signals are superimposed in the control device. A channel signal for the desired detector sensitivity is not required, can be disregarded. For example, a contribution of a channel signal to the detector signal for this purpose can be suppressed in the control device.

Thus, by means of a prefabricated detector arrangement, different sensitivity distributions of the radiation detector can be realized via the control device. The resulting

Detector sensitivity distribution then results from the different weighting of the individual sensitivity channels.

Particularly preferably, the number of different sensitivity channels of the radiation detector corresponds to the number of detector elements.

Different sensitivity channels have their respective maximum sensitivity preferably at different wavelengths.

In a preferred embodiment, the control device has a plurality of inputs via which signals generated in the detector elements can be supplied to the control device. Preferably, different detector elements or different sensitivity channels, in particular in each case, different inputs are assigned. With particular advantage, a separate input is assigned to a detector element or a sensitivity channel.

In a further preferred embodiment, the control device has a plurality of control connections on, by means of which contributions of channel signals to the detector signal can be regulated. Preferably, the number of sensitivity channels corresponds to the number of

Control ports. The contributions of individual channel signals can be set independently via the control connections with preference.

By way of example, the amplification factors for channel signals can be set differently via the control connections with which the channel signals are correspondingly amplified or attenuated relative to one another. For this purpose, the control device expediently comprises a, in particular controllable, amplifier.

Preferably, the control device is designed such that the contributions of channel signals to the detector signal can be controlled externally. The control connections are expediently designed to be externally controllable.

In a further preferred embodiment, the spectral distribution of the detector sensitivity during operation by means of the control device is adjustable. A user can thus set the desired sensitivity distribution of the radiation detector via the control connections.

In a further preferred embodiment, sensitivity channels overlap spectrally. Preferably, the sensitivity channels overlap so spectrally that a spectral detection range of the radiation detector, preferably the visible spectral range, is covered by the overlapping channels. For this purpose, the radiation detector expediently has a plurality of sensitivity channels in the visible spectral range. By way of example, the radiation detector comprises a plurality of spectral sensitivity channels which have a maximum of the spectral distribution at a wavelength in the visible spectral range.

Due to the plurality of sensitivity channels in the visible spectral range, the detector sensitivity can be simplified by means of the control device according to a predetermined distribution.

In a preferred embodiment, the control device is designed such that the radiation detector can be operated or operated as an ambient light sensor with a spectral distribution of the detector sensitivity in accordance with that of the human eye. Appropriately, the sensitivity channels are weighted differently by means of the control device for this purpose, so that results in a superposition of the differently weighted spectral sensitivity channels, a spectral sensitivity distribution according to that of the human eye.

The maximum sensitivity of the light-adapted human eye (daytime vision) is approximately 555 nm. The sensitivity maximum of the dark-adapted human eye (night vision), however, lies in a short-wave range at approximately 505 nm.

By means of the control device, the

Sensitivity channels are weighted so differently that the radiation detector, depending on the setting of the control device, a spectral sensitivity distribution according to that of brightly adapted or dark-adapted human eye.

Preferably, the spectral distribution of the detector sensitivity by means of the control device between those of the light-adapted human eye and the dark-adapted human eye switchable. The switching process can be controlled, for example, by means of a light / dark sensor, which the radiation detector preferably comprises.

In a further preferred embodiment of the radiation detector as a color sensor, in particular for the detection of three primary colors, for. B. red, green and blue, operable. The radiation detector expediently has sensitivity channels which lie spectrally in the region of the corresponding primary colors. Preferably, each of the primary colors is assigned a separate sensitivity channel.

By weakening the other color channels, z. B. by means of a gain of 0 in the control device, which corresponds to a suppression of the respective channel signal contribution, the desired color can be detected in the remaining color channel. Color components in the radiation incident on the radiation detector can then be determined via the detector signal. From these color components can z. B. the color location or the color impression of the incident radiation can be determined.

Preferably, the radiation detector by means of suitable control by the control device both as an ambient light sensor and as a color sensor operable. In a further preferred refinement, the detector arrangement has a semiconductor body which contains at least one of the detector elements. The semiconductor body may comprise a plurality of semiconductor layers and in particular be grown epitaxially. The semiconductor layers are expediently deposited on one another. Preferably, the detector element comprises an active region serving for signal generation. The active region is preferably arranged between two semiconductor layers of different conductivity type-p-type or n-type. These layers are preferably doped. The active region is particularly preferably carried out undoped (intrinsically). The detector element is preferably formed according to a diode structure, for. B. according to a pin diode structure. Pin diodes are characterized by advantageously low response times. The active region preferably contains the compound semiconductor material. Particularly preferably contains a plurality of

Detector elements, in particular the respective active region, the compound semiconductor material, preferably a material from the material system (In, Ga, Al) P. Expediently, a plurality of detector elements formed for the visible spectral range contains the compound semiconductor material.

In a preferred embodiment, a plurality of detector elements is monolithically integrated into a common semiconductor body. Preferably, this semiconductor body has grown epitaxially. The detector elements can be stacked and, in particular, arranged one above the other. Such an arrangement of the detector elements has an advantageously small footprint. In a further preferred refinement, the radiation detector has a plurality of separate, preferably discrete and / or adjacent, detector elements. These elements may each comprise a separate semiconductor body having an active region. The individual detector elements are preferably designed as discrete detector chips. Compared to a monolithic integrated design as described above, individual chips can be manufactured in a simplified manner. An arrangement with a plurality of discrete detector chips, however, is more space-consuming compared to a monolithic training.

In a further preferred embodiment, the radiation detector has three or more, preferably four or more, more preferably five or more sensitivity channels. These sensitivity channels can be in the visible spectral range. The greater the number of different sensitivity channels, the more accurate a given sensitivity distribution of the radiation detector can be reproduced by means of the control device.

In a further preferred embodiment, the radiation detector has one or a plurality of narrowband sensitivity channels. A spectral width of a narrow bandwidth sensitivity channel (full width at half height, FWHM: fill width at half maximum) may be 100 nm or less, preferably 60 nm or less, more preferably 40 nm or less, for example 20 nm or less. By providing a narrow-band sensitivity channel, the radiation detector can be used in a simplified manner for the detection of precisely defined spectral lines. For example For example, a sensitivity channel may be designed such that it responds only to a specific spectral line. The radiation detector can thus be used eg for checking the authenticity of objects which are characterized by this spectral line, such as for bill or check card identification. This function can be provided in addition to the operability as a color sensor or as an ambient light sensor.

In a further preferred embodiment, a single channel signal by means of two, in different

Received detector elements generated signals. For example, a channel signal may be obtained to form the difference of the signals generated in two different detector elements.

A spectral sensitivity channel can accordingly by difference formation from the spectral

Sensitivity distributions of two detector elements are obtained. Particularly preferably, the difference is formed in the control device. The contribution of a channel signal obtained from the subtraction to the detector signal can subsequently also be regulated in the control device.

Such processing of signals from various detector elements simplifies the design of the detector elements for a radiation detector having different sensitivity channels. On a filter for flattening the short-wavelength side of the spectral sensitivity distribution of the respective detector element for the formation of a sensitivity channel can be omitted. The distributions of two, preferably arbitrary, spectral sensitivity channels of the radiation detector expediently intersect at a value less than the maximum of one of the distributions, preferably smaller than the maxima of both distributions. Preferably, the long-wave edge of the distribution with the maximum at the smaller wavelength intersects the short-wave edge of the other distribution.

In a further preferred embodiment, a detector element, preferably a plurality of detector elements, comprises a filter layer. The filter layer preferably absorbs radiation in a wavelength range which comprises wavelengths which are smaller than the wavelength of a maximum of the spectral sensitivity distribution of this detector element. The shortwave edge of the spectral sensitivity distribution of this detector element can be shaped by means of the filter layer for a delimited sensitivity channel. The filter layer is preferably integrated into the semiconductor body of the detector element. The filter layer may be epitaxially grown and / or contain a (III-V) compound semiconductor material.

The filter layer may further determine a short wavelength cut-off wavelength of the respective sensitivity channel.

The formation of the sensitivity channels can therefore already be achieved in the production of the detector elements. A subsequent signal processing, such as the subtraction described above, is not advantageous required. The provision of a corresponding filter layer, however, increases the manufacturing costs of the detector arrangement.

Preferably, the control device is an integrated circuit, for. For example, based on silicon. Integrated circuits may be provided with variable functions and, in particular, may perform the amplification of the individual channel signals for a different weighting of the signal contributions and possibly the formation of the difference for the receipt of a sensitivity channel.

In a further preferred embodiment, the radiation detector has an electronic control device. This is preferably connected to the control device, in particular their control terminals, electrically conductive. The control device is furthermore designed to be programmable. By means of the control device, the settings of the control connections of the control device can be controlled. Thus, the operating state of the radiation detector - e.g. be controlled as a color sensor, as an ambient light sensor or for the detection of predetermined spectral lines - programmed. For example, the switching of the ambient light sensor from day to night sensitivity can be effected by the control device on a daily basis. The control device controls the control connections for this purpose appropriately. The control device is designed, for example, as a programmable microcontroller.

Further advantages, features and advantages of the invention will become apparent from the following description of the embodiments in conjunction with the figures. Figure 1 shows a schematic representation of an embodiment of a radiation detector.

FIG. 2 shows a schematic sectional view of an exemplary embodiment of the detector arrangement, FIG. 2B shows data for the semiconductor bodies of the detector elements from FIG. 2A, FIG. 2C shows the spectral sensitivity distributions of the detector elements, and FIG. 2D shows the sensitivity channels of the sensitivity channels obtained from the sensitivity distributions radiation detector.

FIG. 3 shows a schematic sectional view of a further exemplary embodiment of the detector arrangement on the basis of FIG. 3A, FIG. 3B shows data for the layers of the semiconductor body from FIG. 3A and FIG. 3C shows the sensitivity channels of the detector arrangement.

FIG. 4 shows, with reference to FIG. 4A, that for the spectral sensitivity distribution of the light-adapted human eye and with reference to FIG

Sensitivity distribution of the dark-adapted human eye superimposed sensitivity channels according to Figure 2D.

FIG. 5 shows, with reference to FIG. 5A, the spectral sensitivity channels of a further exemplary embodiment of the detector arrangement and, with reference to FIG. 5B, data for semiconductor layers of the semiconductor bodies for detector elements whose spectral sensitivity distributions correspond to the respective sensitivity channels. FIG. 6 shows a section of a further embodiment of a radiation detector.

The same, similar and equally acting elements are provided in the figures with the same reference numerals. Furthermore, individual elements of the figures are not necessarily reproduced to scale. Rather, individual elements of the figures can be exaggerated for better understanding.

FIG. 1 shows a schematic illustration of an exemplary embodiment of a radiation detector 1.

The radiation detector 1 comprises a detector arrangement 2 and a control device 3. The control device 3 is electrically conductively connected to the detector arrangement 2, so that electrical signals generated in the detector arrangement can be supplied to the control device.

The detector arrangement 2 comprises a plurality of detector elements 4, 5 and 6. The detector elements are expediently designed for radiation reception and signal generation. Preferably, a plurality of detector elements for detecting visible radiation is formed. For example, three detector elements are provided, which are designed for the detection of visible radiation. The detector elements are preferably assigned different detection regions, for example spectral regions of different colors. Thus, the detector element 4 may be designed for detection in the blue spectral range, the detector element 5 for detection in the green spectral range, and the detector element 6 for detection in the red spectral range. A plurality of detector elements, preferably all detector elements designed to detect visible radiation, include

Compound semiconductor material. III-V semiconductor materials from the material system In _y Al _x Gai _x - _y P with 0 ≦ _x ≦ 1 and 0 ≦ _y ≦ 1, preferably with x ≠ 0, y ≠ O, x ≠ 1 and / or y ≠ 1 are particularly suitable for the formation of a radiation detector for the visible spectral range due to the high achievable quantum efficiencies and their insensitivity in the infrared spectral range compared to Si. On external filters for filtering out an infrared portion of the radiation to be detected can in the

Detector arrangement are omitted, since the detector elements themselves can already be formed with a negligible or vanishing sensitivity in the infrared spectral range.

The detector elements 4, 5 and 6 are arranged on a common carrier 7 and preferably mounted on this. The carrier 7 can be formed, for example, by means of a housing, in particular a component housing, preferably a housing for a surface-mountable component. Electrical connections for the detector elements are not explicitly shown for reasons of clarity.

FIG. 2A shows a schematic sectional view of an embodiment of the detector arrangement 2. The detector elements 4, 5 and 6 are designed as discrete detector elements arranged side by side on the carrier 7. For example, the detector elements are designed as discrete detector chips. The detector elements 4, 5 and 6 each have a semiconductor body 401, 501 and 601, respectively. The semiconductor body preferably contains a plurality of semiconductor layers in each case. Furthermore, the detector elements each have a radiation entrance side 402, 502 and 602, respectively. The radiation entrance side is remote from the carrier 7.

The semiconductor body 401, 501 or 601 of the respective detector element comprises an active region 403, 503 or 603. The active region is arranged between two barrier layers 404 and 405, 504 and 505 or 604 and 605. The barrier layers between which the active region is arranged preferably have different conductivity types (p-type or n-type) and are expediently suitably doped for this purpose. The active region comprises a semiconductor functional layer, which is preferably undoped.

The semiconductor bodies of the detector elements 4, 5 and 6 are each arranged on a substrate 406, 506 and 606, respectively. The substrate may be formed by means of the growth substrate of the semiconductor layers for the semiconductor body, on which the semiconductor layers are grown epitaxially.

Furthermore, the detector elements 4, 5 and 6 each have two electrical contacts 407 and 408, 507 and 508 and 607 and 608, respectively. The contacts 408, 508 and 608 may be arranged, for example, on the side of the substrate facing away from the respective semiconductor body. The contacts 407, 507 and 607 may be on that of the respective substrate Be arranged opposite side of the associated semiconductor body. The electrical contacts can be designed as metallizations.

The electrical contacts are expediently electrically conductively connected to the respective active region, so that charge carriers generated in the active region from the respective detector element can be dissipated by absorption of components from a radiation incident on the detector arrangement 2 and the signal thus generated in the detector element is detected can. The signals of the individual detector elements can continue to be detected independently of each other.

The respective semiconductor body 401, 501 or 601 furthermore preferably has a contact layer 409, 509 or 609. The electrical connection of the semiconductor body to the radiation-entry-side electrical contact 407, 507 or 607 can thereby be improved. The contact layer is preferably doped, for example p-type, executed.

The semiconductor layers of the respective semiconductor body are preferably based on compound semiconductor materials. For the visible spectral range III-V semiconductor materials are particularly suitable. The active regions are preferably based on the material system In _y Al _x Gai _x -y P. The Al content can be used to set the band gap of the functional layer, which comprises the respective active region or forms the active region. As a (growth) substrate, a GaAs substrate is particularly suitable for the material system In _y Al _x Gai- _x- P. With regard to good lattice matching to a GaAs substrate, it has proven advantageous to use materials from the sub-material system In _o , 5 (Ga _x Al _x ) ₀ , sP. GaP is particularly suitable for the respective contact layer.

As the Al content increases, the bandgap of a semiconductor layer for the active region increases. In particular, the long-wavelength cut-off wavelength of a spectral sensitivity distribution of the respective detector element can be adjusted by selecting the Al content for the active region. Long-wave radiation, ie radiation whose wavelength is greater than that of the long-wavelength cut-off wavelength, no longer generates any significant signal in the respective detector element. The long-wavelength cut-off wavelength of the detector elements 4, 5 and 6 is preferably in each case in the visible spectral range, it being possible to dispense with external filters, for example for filtering infrared radiation.

The table in FIG. 2B shows exemplary embodiments of materials for the semiconductor layers of the detector elements from FIG. 2A. Furthermore, the layer thicknesses, the respective band gaps (E _G ), the wavelength corresponding to this band gap (λ _G ) and the conductivity type of the respective layers are indicated. The detector element 4 is designed to detect blue radiation, the detector element 5 to detect green radiation and the detector element 6 to detect red radiation.

FIG. 2C shows a simulation of the spectral sensitivity distributions of the detector elements 4, 5 and 6, wherein formation of the semiconductor layers was adopted according to the table in FIG. 2B. The dependency of the responsivity R on the wavelength λ of the incident radiation in nanometers is shown. The responsiveness indicates the strength of the photoelectric current generated in the respective detector element in amperes per watt of the incident radiation power.

The curve 600 represents the spectral sensitivity distribution of the detector element 6, the curve 500 that of the detector element 5 and the curve 400 that of the detector element 4 again. Due to the low Al content, the detector element 6 is already sensitive in the red spectral range. Due to the larger Al content in the orange to green spectral range, the detector element 5 shows high sensitivity values and the detector element 4 is sensitive mainly in the blue spectral range due to the again increased Al content.

The visible spectral range is determined by the

Sensitivity distribution of the light-adapted human eye 700 according to the CIE (Commission Internationale de l'Eclairage) illustrates. In the visible spectral range, all three detector elements show significant sensitivity. Since, for example, a significant signal is generated in all three detector elements in the blue spectral range, it is difficult to obtain color components from the incident radiation directly from the three signals of the detector elements. In particular, the sensitivity distributions do not form distinctly separate sensitivity channels, but rather substantially overlap one another. For example, distribution 600 completely covers the other two distributions. FIG. 3A shows a further exemplary embodiment of a detector arrangement 2 with reference to a schematic sectional view.

In contrast to the detector arrangement according to FIG. 2A, the detector elements 4, 5 and 6 are monolithically integrated into a common semiconductor body 200. The semiconductor body 200 thus comprises the detector elements 4, 5 and 6. The semiconductor body 200 is disposed on a substrate 206 and may be epitaxially grown thereon. The semiconductor body further has a

Radiation entrance side 202 on. The detector elements 4, 5 and 6 are preferably arranged such that the band gap of the functional layer of the respective active region 403, 503, 603 with increasing distance from the

Radiation inlet side 202 decreases. In contrast to the detector arrangement according to FIG. 2A with the discrete detector elements arranged side by side, such a monolithically integrated detector arrangement 2 with a plurality of epitaxially grown detector elements has a smaller space requirement. However, the production cost for such a design of the detector assembly 2 is increased.

The signals generated in the detector elements 4, 5 and 6 can be detected independently of one another via electrical contacts assigned via the detector elements. The detector element 4, the contacts 210 and 211, the detector element 5, the contacts 211 and 212 and the detector element 6, the contacts 212 and 213 assigned. The contacts associated with the respective detector element are electrically connected to the active region of this detector element conductively connected. Two adjacent detector elements each have a common contact. The contacts can be designed as metallizations.

The semiconductor body 200 further has a filter layer 214, which is monolithically integrated into the semiconductor body and in particular can be grown epitaxially. The filter layer 214 is preferably arranged on the radiation entry side in the semiconductor body and particularly preferably absorbs radiation in a wavelength range which comprises wavelengths smaller than the band gap of an active region, in particular the band gap of the active region 403 arranged on the radiation exit side. In the filtered wavelength range, a correspondingly reduced signal is generated in the active regions. The filter layer 214 serves as a window layer to the signal-generating region of the detector arrangement.

FIG. 3B shows a table which contains data for the layers marked correspondingly in FIG. 3A, which were used as a basis for the simulation for the spectral sensitivity distribution of the detector arrangement 2 (cf. FIG. 3C).

The sensitivity distributions 400, 500 and 600 of the detector elements 4, 5 and 6 are shown in FIG. 3C. In contrast to the sensitivity distributions from FIG. 2C, the

Sensitivity distributions of the detector elements formed distinct, spectrally separated sensitivity channels. In particular, the sensitivity distributions only partially overlap one another. Getting from Information about color components in the incident radiation directly from the signals generated in the detector elements is thus simplified with respect to the detector arrangement according to FIG. However, the manufacturing costs are increased accordingly.

Since a large part of short-wave radiation is already absorbed in the radiation-entry-side detector element 4, this contributes only to a reduced extent to signal generation in the downstream detector elements 5 and 6. Therefore, the detector elements 5 and 6 generate a lower signal in the short-wave range than in the case of the detector arrangement shown in FIG. 2A with a plurality of discrete detector elements arranged side by side. Optionally, however, in the case of the discrete detector elements according to FIG. 2, the provision of suitable filter layers, preferably on (In, Ga, Al) P base or (Al) GaAs base, the short-wave edge of the respective sensitivity distribution for a pronounced sensitivity channel by appropriate filtering short-wave Radiation can be suppressed. Corresponding filter layers are preferably arranged in the detector elements 5 and 6 for medium and longer-wave radiation between the radiation entrance side and the active region of the respective semiconductor body.

If, in accordance with the illustration in FIG. 2A, no such filter layers are provided, in order to obtain separate sensitivity channels in the case of a sensitivity distribution according to FIG. 2C, for example, the difference between two sensitivity distributions can be formed. FIG. 2D shows the sensitivity channels obtained from such a difference formation for color detection of the spectral primary colors red, green and blue. Furthermore, the sensitivity distribution 700 of the light-adapted human eye is shown in order to clarify the visible spectral range.

The long-wavelength sensitivity channel 620 is formed from the difference between the long-wavelength sensitivity distributions 600 and the medium-wavelength sensitivity distributions 500 according to FIG. 2C, the medium-wavelength sensitivity channel 520 is formed by the difference between the medium and short-wave sensitivity distributions 500 and 400. The short-wavelength sensitivity channel 420 is formed by the spectral sensitivity distribution of the detector element 4, which is not modified.

In operation of the detector elements 4, 5 and 6, e.g. according to the embodiments of Figures 2 or 3 - signals generated in the detector elements can be supplied to the control device 3 (see Figure 1). Sensitivity channels can already be predetermined by appropriate shaping of the spectral sensitivity distributions of the detector elements (compare, for example, FIG. 3C). Alternatively, signals may be supplied to the control device which are not yet assigned to a preformed sensitivity channel (compare the broad distributions 500 and 600 of FIG. 2C).

The control device has a plurality of inputs (compare the inputs E ₄ , E ₅ and E ₆ ). Expediently, the signals S ₄ , S ₅ or S ₆ generated in the detector elements each become one supplied to the separate input of the control device. Before the signals are fed to the control device, they can still be pre-amplified. In this case, the carrier 7 is preferably designed as a preamplifier, particularly preferably as an amplifier chip, for example based on silicon. The detector elements 4, 5 and 6 in this case with preference in each case an amplifier input VE _{4 Λ} VE ₅ or VE ₆ assigned (compare the elements of the carrier 7 shown in dashed lines in Figure 1).

In the case of discrete detector elements, as described for example in connection with FIG. 2, the individual detector elements are preferably arranged in each case on a separate input of the amplifier chip and connected to this input in an electrically conductive manner. Particularly suitable for this compound is an electrically conductive bonding layer, for example a (silver) conductive adhesive layer.

Since signals of a low intensity, for example of the order of nA or μA, are usually generated in the detector elements, a short connection distance to the amplifier is via a connection layer, for example with a thickness of 1 μm or less, preferably 500 μm or less, particularly suitable. The distance over which the fault-prone "weak" signal is exposed to external electromagnetic interference is advantageously kept low by a conductive layer connection.

Via the respective detector elements associated outputs of the amplifier chip, the preamplified signal to the respective input of the control device 3 are supplied (compare the outputs VA ₄ , VA ₅ and VA ₆ and the preamplified signals SV ₄ , SV ₅ and SV ₆ ). The variant in which the signals of the detector arrangement are pre-amplified, is indicated by the dashed lines to the control device. In this case, each detector element is preferably assigned exactly one amplifier input (VE ₁ , i = 4, 5, 6) and / or amplifier output (VA ₁ , i = 4, 5, 6).

The control device 3 has a control unit 9. The control unit 9 is preferably designed as an amplifier in which channel signals K ₄ , K ₅ and Ke can be amplified from different sensitivity channels, each with different amplification factors. The control unit 9 has control terminals 94, 95 and 96, via which the gain factors for the channel signals from the sensitivity channels can be adjusted independently of each other.

If the detector arrangement does not yet have any preformed sensitivity channels (compare FIG. 2C), the control unit can be configured such that the signals generated in the detector elements are processed in the control device 3 such that channel signals associated with a sensitivity channel are formed. The sensitivity channels are preferably formed in the control device by an element of this device before the signals are supplied to the control unit.

For example, a difference-forming unit 10 may be provided in the control device, which forms differences from the signals obtained from the detector arrangement, whereby the channel signals are formed (see FIG. 2D). In the control unit 9, the relative weights of the channel signals to each other can be set differently.

The differently weighted channel signals can subsequently be superimposed in the superposition unit 11 of the control device 3. Preferably, the overlay unit 11 adds the differently weighted channel signals after passing through the control unit 9. This is indicated by the dashed lines in the overlay unit.

The differently weighted channel signals are superimposed in the superposition unit 11 to the detector signal DS of the radiation detector, in particular added. This detector signal DS can be detected at an output A of the control device 3, which is conductively connected to the superimposition unit 11.

The control device 3 is advantageously designed as an integrated circuit, preferably based on Si. As a result, a small and compact design of the radiation detector 1 is simplified.

By superposing differently weighted channel signals, a radiation detector with different sensitivity distributions-the dependence of the output signal DS on the output A on the wavelength-can be realized.

For example, a radiation detector by different weighting of the channel signals by means of Control unit 9 may be formed as an ambient light sensor having a sensitivity distribution according to that of the human eye. This is shown for the sensitivity channels according to FIG. 2D in FIGS. 4A and 4B.

In Figure 4A, the sensitivity channels are superimposed for a sensitivity distribution similar to that of the light-adapted human eye. For this purpose, signals from the individual sensitivity channels are attenuated or amplified relative to one another. The illustrated superposed sensitivity distribution 701 results from a gain of the sensitivity channel 620 by the factor 0.9, the sensitivity channel 520 by the factor 1.2 and the sensitivity channel 420 by the factor 0.25. The added sensitivity distribution 701 substantially corresponds to that of the light-adapted human eye 700.

In FIG. 4B, the long-wavelength sensitivity channel 620, which is assigned to the red spectral region, is suppressed, which corresponds to a gain factor of 0. The sensitivity channel 520 associated with the green spectral region is amplified by a factor of 0.7 and the sensitivity channel 420 associated with the blue spectral region by a factor of 1.3. The cumulative distribution 703 corresponds approximately to that of the dark-adapted human eye 702. For the distribution of the dark-adapted human eye, for example, the corresponding distribution according to the CIE of 1951 can be used. The spectral distribution of the detector sensitivity is preferably switchable via the control terminals 94, 95 and 96 between that of the light-adapted human eye (distribution 700, Figure 4A) and that of the dark-adapted human eye (distribution 702, Figure 4B). The switching process can be controlled, for example, by means of a light / dark sensor (not explicitly shown), which the radiation detector preferably comprises. The sensitivity channels of the monolithic detector arrangement (see FIG. 3) can also be correspondingly weighted differently and superposed for the particular desired distribution.

In addition to the possibility of operating the radiation detector 1 as an ambient light sensor, it can of course also be used as a color sensor for detecting the basic colors corresponding to the sensitivity channels-in the exemplary embodiments the colors red, green and blue. Color components in the radiation incident on the radiation detector can then be determined via the detector signal. From these color components can z. B. the color location or the color impression of the incident radiation can be determined. Signal contributions from sensitivity channels, which are not assigned to the color to be detected, can be suppressed by setting the control connections accordingly.

Furthermore, a predetermined sensitivity distribution of the radiation detector can be adjusted via appropriate control at the control connections. Of the

Radiation detector is designed to save space overall and advantageously used variably. Figure 5A shows the spectral sensitivity distribution of a detector array having a plurality of separate spectral sensitivity channels 801 ... 809. The

Sensitivity channels are formed by the spectral sensitivity distributions of corresponding detector elements. For this purpose, the detector elements on corresponding filter layers, which between the

Radiation inlet side and the active region of the respective semiconductor body are arranged. By way of example, 9 detector elements can be arranged next to one another analogously to the representation in FIG. 2A, a filter layer being provided between the radiation entrance side and the respective active region in addition to the layer structure shown in FIG. 2A.

Data for the sensitivity distribution of the detector elements was used according to the table in FIG. 5B.

The active areas are each based on the material system In _y Al _x Gai- _x- P. The respective filter layer is based either on the same material system or consists of GaP.

The spectral sensitivity distributions of the detector elements each have a maximum at a wavelength λ _max in the visible spectral range.

Furthermore, the individual sensitivity channels are of narrow band and in particular have at least partial spectral widths of 60 nm or less, preferably 40 nm or less, more preferably 30 nm or less, or even 20 nm or less. This multiplicity of sensitivity channels facilitates, due to the finer distribution of channels over the visible spectral range, on the one hand the exact simulation of a given sensitivity distribution and, on the other hand, the detection of special spectral lines, for example for the verification of check cards or banknotes.

For the detection of special spectral lines, the sensitivity channels not required for the detection of this spectral line are expediently suppressed.

Furthermore, FIG. 5A shows the spectral sensitivity distribution 702 of the dark-adapted human eye. One with the

Amplification factors for the individual sensitivity channels from the table in Figure 5B accumulated

Sensitivity distribution 703 is very similar to that of dark-adapted human eye 702.

The illustrated channels 801 ... 809 are also suitable for color detection, wherein color information is preferably obtained from a plurality of channel signals.

Preferably, the setting of the operating state of the radiation detector - as a color sensor, as ambient light sensor for the brightly adapted eye, as ambient light sensor for the dark adapted eye or possibly as a spectral line sensor - programmatically, for example via a programmable microcontroller. The microcontroller is expediently electrically conductively connected to the control connections 94, 95, 96 of the control device 9. FIG. 6 shows a partial view of the radiation detector 1 according to FIG. 1, in which, in addition to the radiation detector according to FIG. 1, such a microcontroller 12 is electrically conductively connected to the control connections 94, 95, 96 of the control device 9. The further elements of the radiation detector shown in FIG. 1 are not explicitly shown in FIG. 6 for the sake of clarity, but may of course be provided. The control connections are expediently independently controllable by means of the microcontroller. For example, the control terminals 94, 95 and 96 are each electrically connected to a separate electrical contact 124, 125 and 126 of the microcontroller 12.

The microcontroller 12 is preferably programmed so that it the control connections according to fixed predetermined operating conditions of the radiation detector -. B. as a color sensor, as an ambient light sensor for the brightly adapted eye, as an ambient light sensor for the dark adapted eye or as a spectral line sensor - drives. A user can then freely switch between the predetermined operating conditions via appropriate response of the microcontroller. A user-consuming determination of the most appropriate for the respective operating state adjustment of the control connections relative to each other can be avoided. Rather, these settings can already be carried out at the factory by appropriate programming of the microcontroller.

Alternatively or additionally, the microcontroller can control the operating state in time, eg with regard to the time of day. For example, the microcontroller can do this be programmed that he allows from a certain time of day, preferably after onset of dusk, during operation of the radiation detector as the ambient light sensor only the detection according to the dark adapted human eye. Preferably, the microcontroller is programmable by the user, so that a switching between operating states, in particular a time-controlled switching, of the radiation detector can be preset by the user.

This patent application claims the priorities of German patent applications 10 2006 056 579.7 of 30 November 2006 and 10 2007 012 115.8 of 13 March 2007, the entire disclosure of which is hereby explicitly incorporated by reference into the present application.

The invention is not limited by the description with reference to the embodiments. Rather, the invention encompasses any novel feature as well as any combination of features, including in particular any combination of features in the claims, even if this feature or combination itself is not explicitly stated in the patent claims or exemplary embodiments.

Claims

claims

A radiation detector (1) having a detector arrangement (2) which has a plurality of detector elements (4, 5, 6), by means of which a detector signal (DS) is obtained during operation of the radiation detector, and a control device (3)

- The detector elements each have a spectral

Have sensitivity distribution (400, 500, 600) and are suitable for signal generation (S4, S5, Sg),

at least one detector element contains a compound semiconductor material and this detector element is designed to detect radiation in the visible spectral range,

- The radiation detector is designed such that by means of the sensitivity distributions of the detector elements different spectral sensitivity channels (420, 520, 620) of the radiation detector are formed,

- In the sensitivity channels by means of the detector elements a respective sensitivity channel associated channel signal (K4, K5, Kg) can be generated, and

- The control device is designed such that the contributions of different channel signals are regulated differently to the detector signal of the radiation detector.

2. The radiation detector of claim 1, wherein the control device weights contributions from channel signals to the detector signal relative to each other differently.

3. Radiation detector according to claim 1 or 2, wherein the detector signal of the radiation detector is formed by means of superposition of channel signals.

4. Radiation detector according to at least one of the preceding claims, wherein the control device has a plurality of inputs (E4, E5, Eg), are supplied via the signals generated in the detector elements of the control device, and different inputs are assigned to different detector elements.

5. Radiation detector according to at least one of the preceding claims, wherein the control device has a plurality of control terminals (94, 95, 96), by means of which contributions of channel signals to the detector signal can be regulated.

6. Radiation detector according to at least one of the preceding claims, in which a single channel signal is obtained by means of two signals generated in different detector elements.

7. Radiation detector according to at least one of the preceding claims, wherein a channel signal is obtained to form the difference (10) of the signals generated in two different detector elements.

8. Radiation detector according to at least one of the preceding claims, wherein the sensitivity channels overlap spectrally.

9. Radiation detector according to at least one of the preceding claims, in which the sensitivity channels overlap in such a way that the visible spectral range is covered.

10. Radiation detector according to at least one of the preceding claims, wherein the control device is designed such that the radiation detector as an ambient light sensor with a spectral distribution of the detector sensitivity according to that of the human eye (700, 702) is operable.

11. A radiation detector according to claim 10, wherein the spectral distribution of the detector sensitivity by means of the control device between the light-adapted human eye (700) and the dark-adapted human eye (702) is switchable.

12. Radiation detector according to at least one of the preceding claims, which is used as a color sensor, in particular for the detection of three primary colors, e.g. Red, green and blue, is operable.

13. Radiation detector according to claim 12 and claim 10 or claim relating back to claim 10, which is operable by means of the control device both as an ambient light sensor and as a color sensor.

14. Radiation detector according to at least one of the preceding claims, the detector arrangement has a, in particular epitaxially grown, semiconductor body (200, 401, 501, 601) which contains at least one of the detector elements.

15. A radiation detector according to claim 14, wherein the detector element one of the signal generation having active region (403, 503, 603) containing the compound semiconductor material.

16. A radiation detector according to claim 14 or 15, wherein a plurality of detector elements is monolithically integrated in a common semiconductor body (200).

17. Radiation detector according to at least one of the preceding claims, which has a plurality of separate, juxtaposed detector elements.

18. A radiation detector according to at least one of the preceding claims, wherein a plurality of detector elements containing the compound semiconductor material.

19. Radiation detector according to at least one of the preceding claims, in which a plurality of detector elements for detecting radiation in the visible spectral range is formed.

20. Radiation detector according to at least one of the preceding claims, which has three or more, preferably four or more, more preferably five or more sensitivity channels.

21. Radiation detector according to at least one of the preceding claims, having one or a plurality of narrow-band sensitivity channels (801 ... 809).

22. Radiation detector according to at least one of the preceding claims, wherein the compound semiconductor material is a III-V semiconductor material, preferably a

Compound semiconductor material from the material system (In, Al, Ga) P, is.

23. Radiation detector according to at least one of the preceding claims, wherein the control device is designed as an integrated circuit.