DE102008011280A1 - A radiation-receiving semiconductor device, method for operating and using the same, and radiation detector and semiconductor device with the semiconductor device - Google Patents

Abstract

The invention relates to a radiation-receiving semiconductor component having a semiconductor body and a radiation entrance side, the semiconductor body having a detection region provided for radiation reception, at least two electrical contact regions and at least one doped barrier region, a current path extending between the contact regions in the semiconductor body, the barrier region and the detection region in the current path are arranged between the contact region and the barrier region is suitable for forming a potential barrier which is arranged between the detection region and the contact region which, viewed along the current path, lies on the side of the barrier region facing away from the detection region.

Description

The The invention relates to a radiation-receiving semiconductor component and a method of operating the semiconductor device.

For radiation detectors based on semiconductors, for example, avalanche photodiodes can be used as semiconductor components (English: Avalanche Photo Diode, in short: APD). As an avalanche photodiode is suitable, for example, a reverse biased pin diode. The operating voltage (blocking voltage) of the diode is chosen so that the diode goes into the state of avalanche breakdown when a single electron-hole pair in the intrinsic (i) zone occurs. By avalanche multiplication of the electrons and holes in the breakdown state, a significant measurable signal can be obtained to which both the electrons and the holes contribute. Achieving the breakdown state typically requires high field strengths, for example of 10 ⁵ V / cm or more, and thus high reverse voltages, for example of 100 V or more.

at constant operating voltage, the diode remains in the breakdown state. To the diode back to the initial state - so the unbroken Condition - too bring and the diode thus again for a further radiation detection To make ready, a high impedance resistor can be used in series with the Diode are switched. The avalanche current can flow away via the resistor. The voltage drop over the Resistance leads to a reduction of the voltage at the diode (so-called quenching). Due to the voltage drop across the resistor, the field strength drops in the Diode up under the for value required for avalanche breakthrough. The current flowing through the diode dried up in the episode.

at the APD can also thermally or by tunneling, for example band-to-band tunneling, generated electron-hole pairs trigger the avalanche breakdown. The So diode can deliver a signal without any to be detected Photon has invaded.

A to be solved The object is an improved radiation-receiving semiconductor component and to provide a method of operating this device.

These Problem is solved for example by the subject matters of the independent claims. advantageous Embodiments and further developments are the subject of the dependent claims.

According to one embodiment a radiation-receiving semiconductor component has a semiconductor body and a radiation entrance side. About the radiation entrance side can reach radiation to be detected in the semiconductor body, there are absorbed and subsequently generate a charge carrier pair, in particular an electron-hole pair.

Of the Semiconductor body has a for the radiation reception provided detection area, at least two electrical contact areas and at least one barrier area on. Between the contact regions, a current path extends in the semiconductor body. On the Rung can In the operation of the semiconductor device charge carriers in the semiconductor body of flow one contact area to the other contact area. Of the Barrier area and the detection area are in the current path arranged between the contact areas. The barrier area is preferably carried out doped.

Of the Barrier region is furthermore preferred for forming a potential barrier suitable and in particular provided. The potential barrier is preferred formed between the detection area and that contact area and in particular, which is seen along the current path on the side of the barrier area facing away from the detection area is arranged. about In the operation of the semiconductor device, the potential barrier can For example, at a created between the contact areas Contact voltage, a charge carrier flow from hindering one contact area in the other contact area or even prevented. The barrier area can be designed in this way be that a charge carrier flow from one contact area to the other contact area in front of one Radiation absorption in the detection area is omitted and after a Radiation absorption charge carriers from one to the other contact area can flow.

In In a preferred embodiment, the semiconductor device is such designed and in particular operable that in the semiconductor body, preferably in the detection area, a primary charge carrier, for For example, an electron or a hole, by impact ionization secondary charge carriers, for example an electron-hole pair or a plurality of electron-hole pairs, can generate. The primary charge carrier, preferably an electron can be detected by absorption of radiation to be detected be generated in the detection area.

In a further preferred embodiment, the semiconductor component is designed and in particular operable such that a flow of charge carriers, for example of secondary charge carriers and / or charge carriers of a unitary Chen charge carrier type (electrons or holes), which are generated in the semiconductor body and in particular in the detection area, from the detection area through the barrier area and in that contact area, which is seen along the current path on the side remote from the detection area of the barrier area, during operation of the device can be hindered or even prevented by means of the potential barrier. Preferably, the charge carrier flow from one to the other contact area temporarily, more preferably only temporarily prevented or hindered.

In Another preferred embodiment is the semiconductor device designed and in particular operable such that in the semiconductor body and in particular in the detection area generated charge carriers, for Example secondary carriers, one Charge carrier type drift to the barrier area and collect in the barrier area can. By The charge carriers accumulated in the barrier region can be the height of the potential barrier be reduced.

The charge carrier of the charge carrier type can in Barrier region of ionized Dotierstoffatomrümpfen electrostatically attracted become. The charge carriers accumulated in the barrier region can interact with recombine the ionized Dotierstoffatomrümpfen. Electrons as charge carriers this charge carrier type are expediently attracted by positively charged Donatoratomrümpfen. Be holes as a charge carrier this charge carrier type expediently attracted by negatively charged acceptor atoms. The in the barrier area collecting charge carriers are preferably secondary carriers. by virtue of the higher one effective mass are holes for the Accumulation in the barrier area particularly suitable. Electrons are suitable especially for the generation of secondary carriers by impact ionization, especially due to the lower effective mass in comparison to holes.

In Another preferred embodiment is the semiconductor device designed or in particular operated so that after reduction the potential barrier charge carrier from a contact area through the barrier area and the detection area can flow into the other contact area. The charge carriers, the from the one flow into the other contact area are preferably carriers of the other type of charge carrier - for example charge carrier of the type that does not collect in the barrier area or through the potential barrier is hindered. Preferably, the charge carriers of other type of charge electron.

This has the advantage that a signal from the detector is not exclusive of the impact ionization like in an avalanche photodiode but rather by a charge carrier flow of one contact area to the other contact area, which after sufficient Reduction of the potential barrier begins. The semiconductor device can as a unipolar component, ie as a component in which only carriers of a Charge carrier type, preferably electrons contribute significantly to the signal formed be.

In a further preferred embodiment, the semiconductor device a control electrode. This is preferred for the application of an electrical Control field to the barrier area suitable and particularly preferred intended. The control panel can by means of a to the control electrode applied control voltage or one to the control electrode created control potential. The control electrode can about the Extend barrier area. about the control electrode and in particular the control voltage applied there or the control potential applied there can be the height of the potential barrier to be controlled. Conveniently, is between the control electrode and the semiconductor body Dielectric arranged. The dielectric, for example a dielectric layer, isolated with preference the control electrode, in particular the entire surface of the Semiconductor body. The dielectric is expediently designed such that an electrical breakdown to the control electrode is avoided during operation of the semiconductor device. The control electrode extends prefers over the detection area. By applying a suitable control voltage or a suitable control potential to the control electrode In the detection range, a conductive channel for the charge carrier passage be formed by the detection area. The channel can for Example be an n-channel. The charge carrier passage through the detection area after the degradation of the potential barrier is facilitated.

Becomes during operation of the semiconductor device, a photon in the detection area absorbed, can by means of the charge carrier generated by absorption more charge carriers impact ionization be generated in the detection area. By drifting to the barrier area charge carrier can the barrier height can be reduced and it can flow a signal current. The Semiconductor device is especially for the detection of single photons or radiation pulses, in particular ultrashort pulses, for example in the nanosecond, picosecond or femtosecond range and preferably formed. Furthermore, the semiconductor component is suitable as a photon counter.

According to one embodiment a semiconductor device comprises a plurality of radiation-receiving Semiconductor devices of the type described above. The semiconductor device can monolithic integrated running be. For example, the semiconductor device may be ten or more, preferably twenty or more, semiconductor devices. By a plurality of semiconductor devices, the available detection area increased. The Semiconductor arrangement can in particular one for all semiconductor devices the semiconductor device common substrate, in particular a semiconductor substrate, exhibit. This substrate may form one of the contact areas.

According to one embodiment For example, a radiation detector includes a semiconductor device or a semiconductor device Semiconductor device of the type described above. The radiation detector is preferred for the detection of radiation with wavelengths outside the spectral sensitivity range of the detection range suitable and particularly preferably formed. In this case, the radiation detector points prefers a conversion element which receives incident radiation, So radiation that does not absorb in the detection area and accordingly also would not produce an electron-hole pair, converted into radiation, which can be absorbed in the detection area. The radiation detector This can be used to specific wavelength ranges of the detected Radiation can be adjusted without changing the detection range would. This has advantages in the manufacture of the semiconductor devices for a Radiation detector, since these can be prefabricated similar and with different conversion elements to different to be detected wavelength can be adjusted. For example For example, the radiation detector can be designed to detect X-radiation be. For this purpose, a scintillator can be provided as a conversion element be.

One Semiconductor device, a semiconductor device or a radiation detector as described above is also suitable for the analysis of the composition a sample material, for example via detection of means of Sample material generated radiation, in particular γ-radiation or of X-rays.

In an embodiment a method of operating a radiation-receiving semiconductor device, a semiconductor device or a radiation detector of the above described type is first a contact voltage between the two contact areas created. This can be a extending through the detection area form electrical field in the semiconductor device and in particular in the semiconductor body. The contact voltage and the semiconductor body, in particular the contact voltage and the detection area, are matched to each other, that in the detection range generated by absorption charge carriers of a Charge carrier type in the semiconductor body and in particular generate additional charge carriers by impact ionization in the detection area can. The potential barrier formed by the barrier region and the contact voltage will continue to match each other so that a signal current flow from one contact region to the other Contact area is prohibited.

When Signal flow is a signal from a background noise, which caused for example by a dark current, significantly to understand different current signal.

following is radiation, in particular a single photon or a radiation pulse, absorbed in the detection area. At least one primary charge carrier of a Charge carrier type, For example, an electron or a hole generated in the detection area. By impact ionization through the primary carrier then secondary charge carriers, in particular Electron-hole pairs generated in the detection area. For impact ionization will the primary charge carrier expediently accelerated in the electric field in the detection area such that impact ionization occurs. Secondary carrier of a Charge carrier type, for example holes, drift to the barrier area and gather there so the Potential barrier is reduced. Also by secondary carriers can optionally impact ionization generates additional secondary carriers become. Altogether so can a multiplicity of secondary load carriers in the Collect barrier area. The potential barrier can be controlled by the secondary charge carriers of a Charge carrier type be reduced in particular such that a signal current of flows one contact area to the other contact area. there flows the signal current expediently through the barrier area and the detection area.

Of the flowing Signal current can be detected below. Is a stream flowing this means that radiation has hit the detection area.

The Charge carriers accumulated in the barrier region are not preferred or not essential to the signal current.

The height of the potential barrier is expediently selected such that it can be reduced to such an extent by charge carrier accumulation of secondary charge carriers generated by impact ionization that a signal current through the contact area can flow.

In front the radiation absorption can be a predetermined control voltage or a predetermined control potential, which (s) to form a suitable for the signal current flow by means of the secondary charge carrier degradable potential barrier is, determined and applied to the barrier area. This conveniently takes place over the Control electrode. about the control electrode can adjust the height the potential barrier can be varied. The control electrode can thus used for operating point adjustment of the semiconductor device become.

After this the signal flow has flowed and in particular has been detected by Applying a suitably poled voltage, for example a suitable polarized control voltage or a suitable control potential, At the barrier area, the secondary charge carriers drifted into the barrier area the barrier area deducted ("sucked"). This removal leads to allow the barrier to rebuild and the signal current flow is subsequently suppressed.

To removal of the secondary carrier the barrier area, the radiation detector is back in the initial state, so that another detection process can be started.

Of the Process of sucking the secondary carrier from The barrier area is advantageously feasible faster than the degradation of the very high reverse voltage across the avalanche photodiode by the initially described quenching.

Farther For example, the semiconductor device can be compared with an avalanche photodiode be operated with a low voltage advantageous. This results from it, that by impact ionization generated charge carriers essentially serve only the degradation of the barrier and not how at the avalanche photodiode must contribute significantly to the signal. The contact voltage can 75 V or less, preferably 60 V or less, more preferably 50 V or less. The contact voltage can be 20V or more, preferably 30 V or more, more preferably 40 V or more be. Due to the advantageous low contact voltage can at a semiconductor device, the individual semiconductor devices denser be packed without the risk of electrical (voltage) breakdown between two adjacent semiconductor devices to increase. The Quantum efficiency per area can be increased with advantage become.

Further Advantages, features and advantageous embodiments arise from the following description of the embodiments in conjunction with the figures.

1 shows an embodiment of a radiation-receiving semiconductor device with reference to a schematic sectional view.

2 shows by the 2A . 2 B and 2C schematic energy band diagrams for different operating states of the semiconductor device according to 1 ,

3 shows a plan view of an embodiment of a semiconductor device having a plurality of semiconductor devices.

4 shows a schematic sectional view of an embodiment of a radiation detector.

5 shows a further embodiment of a radiation-receiving semiconductor device based on a schematic sectional view.

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

1 shows an embodiment of a radiation-receiving semiconductor device 1 using a schematic sectional view.

The radiation-receiving semiconductor device 1 has a semiconductor body 2 on. The semiconductor device further has a radiation entrance side 3 on.

The semiconductor body 2 has two electrical contact areas 4 . 5 on. Between the contact areas 4 and 5 , in particular of the contact area 5 up to and into the contact area 6 , extends an electrical current path 6 in the semiconductor body 2 , In the current path 6 between the contact areas 4 and 5 and in particular also spatially between the contact areas is a detection area 7 of the semiconductor device 1 in the semiconductor body 2 arranged. The semiconductor body 2 also has a barrier area 8th on. The barrier area 8th is in the current path 6 between the detection area 7 and the contact area 5 and in particular also spatially between the detection area 7 and the contact area 5 arranged. The barrier area 8th is preferably on the from the radiation entrance side 3 opposite side of the detection area 7 arranged.

Furthermore, the semiconductor body 2 one stopband 9 on. The restricted area 9 is in the current path 6 between the barrier area 8th and the contact area 5 and in particular also spatially between the barrier area 8th and the contact area 5 arranged.

The semiconductor body 2 may comprise a layer stack, wherein in each case layers for the contact area 5 , the restricted area 9 , the barrier area 8th , the detection area 7 and / or the contact area 4 are provided. So it can be a contact layer 4 , a detection layer 7 , a barrier layer 8th , a barrier layer 9 and / or a contact layer 5 be provided. The respective layers may be embodied as separate layers. In particular, the respective layers may be grown epitaxially, for example by MBE (MBE: molecular beam epitaxy) or by means of a CVD epitaxy process (chemical vapor epitaxy). The contact area 5 may be formed by the growth substrate on which the layers are epitaxially deposited. So it does not necessarily have a separately grown contact layer 5 be provided, but this can be used to the growth substrate, as in 1 is shown.

This in 1 shown component is designed as a vertical component. In a vertical component layers for the individual areas can be stacked one above the other. A current flow can be vertical or substantially perpendicular to a lateral main extension direction of the layer stack of the semiconductor body in vertical components 2 take place, which can be aligned along a main surface of the substrate.

After the epitaxial growth of the individual layers for the semiconductor body, a mesa can be formed from the epitaxial layers. For example, reactive ion etching using a suitable mask, for example a (metal or nitride) hard mask, is suitable for this purpose. The mesa may be from the radiation entrance side 3 of the semiconductor device 1 which is preferably the side of the semiconductor layer stack facing away from the substrate, up to or even into the contact region 5 , So possibly extend into the substrate.

The contact area 5 , the restricted area 9 , the barrier area 8th , the detection area 7 and / or the contact area 4 may contain silicon or consist of silicon, wherein individual areas may optionally be carried out doped.

The radiation-receiving semiconductor device 1 has two electrical connections 10 . 11 on. It is expediently the connection 10 on the contact area 4 and the connection 11 on the contact area 5 arranged. The respective connection 10 . 11 is with the associated contact area 4 respectively 5 suitably connected electrically conductive. About the connections 10 and 11 may be a signal current passing through the contact areas 4 . 5 and the semiconductor body 2 flows, be detected in a simplified manner. The connections can be designed, for example, in each case as a connection metallization or connection alloy. A metal or metal-like material is for the connection 10 or 11 particularly suitable.

Furthermore, the semiconductor device 1 a control electrode 12 on. The control electrode 12 may be along a side surface of the semiconductor body 2 which bounds this laterally and preferably from the radiation entrance side 3 in the direction of the contact area 5 extends, extend. The control electrode 12 can be especially about the detection area 7 , the barrier area 8th and / or the restricted area 9 extend. The control electrode 12 may include silicon, for example highly doped poly-silicon, or another electrically conductive material, for example a metal or a metal alloy. The control electrode 12 is preferred with a control port 13 , For example, a metallization or metal alloy electrically conductively connected. The control electrode may be the detection area 7 , the barrier area 8th and / or the restricted area 9 circulate. About the control electrode 12 and in particular the control terminal 13 may be a control voltage or an electric control field to the semiconductor body 2 and in particular to the detection area 7 , the barrier area 8th and / or the restricted area 9 be created.

Between the control electrode 12 and the semiconductor body 2 is a dielectric layer 14 arranged. Over the dielectric layer 14 is the control electrode 12 electrically from the semiconductor body 2 isolated. The dielectric layer can be realized for example by thermal growth or by deposition on the semiconductor body. For example, a silicon oxide, a silicon nitride or another electrically insulating material is suitable for the dielectric layer. A thickness of the dielectric layer 14 is suitably dimensioned such that when applying a predetermined contact voltage between the contact areas 4 and 5 and the simultaneous application of a suitable for the operation of the device control voltage or a suitable control potential by means of the control electrode, an electrical breakdown of one of the contact areas 4 . 5 or one of the connections 10 . 11 to the control electrode 12 is avoided. For example, the dielectric layer has a thickness of 10 nm or more, preferably 20 nm or more, more preferably 50 nm or more, for example, 70 nm or more, or 100 nm or more.

The dielectric layer 14 can the detection area 7 , the barrier area 8th and / or the restricted area 9 Dress up laterally on the outside.

The detection area 7 is intended for the absorption of radiation to be detected, which via the radiation entrance side into the semiconductor body 2 incident. To an unwanted radiation absorption in the detection area 7 Radiation inlet side upstream elements to avoid, in the semiconductor body 2 on to the detection area 7 reaching window 15 be educated. The radiation inlet side arranged contact area 4 can for the window 15 be omitted. In particular, the connection can also 10 be omitted.

Radiation can thus unhindered by the material of the semiconductor body 2 or the connection 10 , in which a significant proportion of radiation can be absorbed, the absorbed radiation is therefore no longer to the detection area 7 enters, enter the detection area. The risk of absorption losses is thus reduced. Particularly high absorption losses often result in doped semiconductor material or in metals.

To the radiation entry into the detection area 7 To facilitate, may be on the detection area 7 Radiation inlet side an antireflection coating 16 , For example, a suitable Siliziumoxyd- or Siliziumnitridbeschichtung be arranged. Reflection losses at a radiation entrance surface 17 in the detection area can be at least reduced.

The anti-reflective coating 16 is preferably within the window 15 arranged.

The radiation-receiving semiconductor device 1 is preferably suitable for the detection of single photons or radiation pulses, in particular ultrashort radiation pulses, for example with a pulse duration of 500 ns or less, of 900 ps or less or of 100 fs or less, suitable and in particular designed. At low numbers of photons, an absorption outside the detection range or a reflection at the detection range, which in each case does not lead to a radiation entry into the detection range, of course, particularly significant.

The detection area 7 is designed such that secondary charge carriers can be generated via impact ionization of primary charge carriers. A primary charge carrier may be, for example, an electron or hole produced by absorption of radiation in the detection region. The detection area points along the current path 6 preferably has an extension, for example a thickness, which is large enough to be able to achieve one or a plurality of impact ionizations with the primary charge carrier. The path length available for accelerating the charge carriers for the generation of secondary charge carriers by impact ionization is then advantageously sufficiently large. However, it may also be advantageous not to form the detection area with too great an extent, for example the thickness, in order to avoid a recombination of secondary charge carriers generated by impact ionization in the detection area.

An extension of the detection area 7 along the current path, for example the thickness, of between and including 100 nm and 1000 nm inclusive, preferably between 200 nm and 900 nm inclusive, more preferably between 300 nm and 800 nm inclusive, for example between 350 nm and 500 nm, such as 400 nm, has proved to be particularly suitable. Such expansions both provide a sufficiently long distance to create secondary carriers and at the same time do not increase the risk of recombination.

The barrier area 8th is expediently designed such that during operation of the device, a charge carrier flow in the detection area 7 charge carriers generated by absorption and / or impact ionization through the barrier region and to the contact region 5 , preferably only temporarily, can be prevented. By means of the barrier area 8th in particular, a potential barrier between the detection area 7 and the contact area 5 be educated. The height of the potential barrier can via the to the control electrode 12 applied control voltage or the applied control potential can be set.

About the restricted area 9 may be a charge carrier tunneling from the barrier area 8th in the contact area 5 be prevented. This has the advantage that a tunnel current can not contribute to the dark current of the component, or can do so only with great difficulty. The stopband may have an extension along the current path that is less than that of the detection region. The extent of the restricted area 9 For example, the thickness may be 20 nm or more and / or 50 nm or less.

The detection area 7 can be an extension along the current path 6 that the Eight times or more the extent of the stopband along the current path 6 is.

The barrier area 8th may have an extension along the current path, for example, a thickness of 20 nm or less, preferably 15 nm or less, more preferably 12 nm or less. The extent is preferably 3 nm or more, more preferably 5 nm or more, for example, 10 nm or more. An extension of the barrier area of between each including 10 nm and 20 nm has been found to be particularly suitable for the barrier area.

The contact areas 4 . 5 and the barrier area 8th are expediently doped, in particular n-type or p-type doped. The contact regions and the barrier region can be doped for the same conductivity type (p-type or n-type). The contact areas may alternatively be doped for different types of lines. The barrier area 8th may be doped for a different type of line than one of the contact areas 4 . 5 or both contact areas.

The detection area 7 and / or the restricted area 9 is preferably intrinsic, that is undoped, executed.

The structure of the radiation-receiving semiconductor device 1 can thus correspond to that of a modified MOSFETs, wherein the contact area 5 as source, the contact area 4 as drain and the control electrode 12 serves as a gate electrode. Between the barrier area 8th and the drain is the detection area 7 arranged. Between the source and the barrier area 8th is the restricted area 9 arranged.

Due to a to the control electrode 12 applied control voltage or an applied control potential may be an electrically conductive channel, for example, an n-channel or a p-channel, along the current path 6 in areas of the semiconductor body 7 over which the control electrode 12 extends, for example in the detection area 7 and / or the restricted area 9 to train.

The semiconductor device 1 is further preferably designed such that in operation in the energy band diagram along the current path 6 between the contact areas 4 and 5 forms a potential barrier. The potential barrier preferably has a triangular shape. A triangular shaping of the potential barrier has proven to be a generation of charge carriers by impact ionization in the detection area 7 particularly suitable. The potential barrier is expediently by means of the barrier region 8th educated.

2 shows by the 2A . 2 B and 2C schematic energy band diagrams for different operating states of the semiconductor device 1 according to 1 ,

2A shows the energy band course along the current path 6 from the contact area 4 over the detection area 7 , the barrier area 8th , the restricted area 9 to the contact area 5 , Between the contact areas 4 . 5 there is no potential difference (contact voltage) applied. Furthermore, no control potential difference (control voltage) by means of the control electrode 12 applied to the semiconductor body.

shown are the valence band V, the conduction band L and the Fermi level F.

The contact areas 4 . 5 are doped n-type, for example. The detection area 7 and the restricted area 9 are for example intrinsically (i) executed. The barrier area 8th is for example p-doped. The barrier area 8th is preferably highly doped (p ⁺⁺ ), for example with a dopant concentration of 1 × 10 ¹⁹ l / cm ³ or more, preferably of 1 × 10 ²⁰ l / cm ³ or more, particularly preferably of 5 × 10 ²⁰ l / cm ³ or more trained. The contact areas 4 . 5 may be formed at a dopant concentration of 1 × 10 ²⁰ L / cm ³ or less.

The individual areas can based on silicon. For For example, an n-doping is phosphorus as a dopant and for For example, boron is used as dopant for a p-type doping.

Furthermore, the Dotierprofilverlauf along the current path at the transition from the detection area 7 to the barrier area 8th preferably a steep increase in dopant concentration. At the transition from the barrier area 8th to the restricted area 9 For example, there may be a steep drop in the dopant concentration.

The dopant profile of the barrier area with respect to the adjacent areas - for example the (intrinsic) detection area 8th and in particular the (intrinsic) stopband 9 - may be approximate to a Dirac δ function. Therefore, such a highly doped and preferably thin barrier layer layer can also be referred to as δ-layer.

The dopant concentration of the dopant of the barrier region 8th may be particularly preferred in the transition from outside the barrier area to the barrier area or within the barrier area over a distance of 10 nm or less along the current path by five times or more, preferably seven times or more nine times or more. A barrier region doped with such a sharp transition in the dopant profile is particularly advantageous for the formation of an electric field by the potential gradient in the detection region, the electric field being suitable for generating secondary charge carriers by impact ionization during operation of the semiconductor component.

Between the contact areas 4 . 5 a triangular shaped potential barrier P is formed. Conveniently, the detection area 7 and the barrier area 8th and optionally the restricted area 9 coordinated so that the triangular-shaped potential barrier results in the energy band diagram. The barrier area 8th is arranged in the region of the tip of the triangle, wherein the triangular tip can be made flattened as shown. The length of the flattened piece may be the thickness of the barrier area or less than the thickness of the barrier area.

2 B shows the energy band diagram 2A with one at the contact areas 4 . 5 applied contact voltage V _K.

The voltage is applied so that the electrical potential at the contact area 4 greater than the electrical potential at the contact area 5 is (positive contact voltage). This results in the energy bands L, V being on the contact area 4 move down. The shift may be proportional to V _K.

The Contact voltage may be 75 V or less, preferably 60 V or less, particularly preferably 50 V or less. The contact voltage in particular between in each case including 20 V and 75 V, preferred between each one inclusive 30V and 60V, more preferably between each including 40 V and 50 V, lie.

In this case, the majority of the contact voltage over the detection range 7 fall off.

In particular, a steep potential gradient forms from the barrier area 8th over the detection area 7 to the contact area 4 , The potential gradient may be 10 ⁴ V / cm larger, preferably 5 × 10 ⁴ V / cm or larger. Such a large potential gradient is particularly suitable for impact ionization.

Between the contact areas 4 . 5 the potential barrier P is formed. So no signal current flows from the contact area 5 to the contact area 4 , The semiconductor device 1 is thus biased so that no signal current from the Kotaktbereich 5 to the contact area 4 flows.

If a photon is absorbed in the detection area, a primary electron-hole pair (E _p , H _p ) is formed. The electron E _p is along the potential gradient, which is in particular caused by the potential barrier and the contact voltage, in the direction of the contact region 4 accelerates and can generate secondary electron-hole pairs (E _s , H _s ) by impact ionization. This is indicated by the arrows in the conduction band L and the double arrows between conduction band L and valence band V. The electrons - primary and secondary electrons - flow to the contact area 4 (Drain).

The by impact ionization in the detection area 7 generated holes - primary and secondary holes - flow to the barrier area 8th , The holes are characterized by the potential gradient especially in the direction of the barrier area 8th accelerated. In the barrier area 8th are due to the p-type doping numerous negatively charged acceptor atomic hulls available. Through the in the barrier area 8th At least part of the negative charges of the acceptor atomic bodies are compensated, so that the height of the potential barrier P is reduced, reaching, positively charged and accumulating holes. The holes can in particular recombine with the dopant fumes in the barrier region.

2C shows the situation after reducing the potential barrier P.

The height of the potential barrier can be solely due to the accumulation of secondary charge carriers in the barrier region 8th be reduced so much that a signal current I, in particular of the majority charge carriers of the contact areas - in the present case the electrons - is worn, from the contact area 5 (Source) to the contact area 4 (Drain) flows. The signal current may have a magnitude of 0.1 mA or more, preferably 1 mA or more. Conveniently, the semiconductor device 1 dimensioned such that it can pass through such streams non-destructive.

The in the barrier area 8th Accumulated holes remain after the degradation of the potential barrier to the signal current flow preferably in the barrier area. The holes can be kept in the barrier area in particular by the previously ionized dopant atoms and / or already be recombined with them. Furthermore, holes have a higher effective mass than the electrons, so that even a comparatively small residual potential barrier is sufficient to hold the holes in the barrier region, while the electrons can overcome such a residual potential barrier as opposed to the holes.

Holes do not wear or are preferred least not significant to the signal current I at. The component is thus a unipolar component whose current is carried only by charge carriers of a charge carrier type (in the present example: electrons).

The charge carriers E _s , H _s generated by impact ionization do not contribute significantly to the signal, but rather serve only for barrier degradation and enable a signal current flow through the degradation of the barrier.

The height of the potential barrier is preferably dimensioned such that at a predetermined contact voltage before the radiation incidence no signal current between the contact areas 4 . 5 flows. Furthermore, the height of the potential barrier is on the detection area 7 and / or the contact voltage V _K expediently adjusted such that the potential barrier can be reduced by charge carriers generated by impact ionization to such an extent that, advantageously already caused by the incidence of a single photon, a signal current can flow between the contact regions.

The barrier height can expediently by the control electrode 12 and in particular via an electric control field applied to the barrier area by means of this control electrode or an applied control voltage or control potential V _S. By means of the control electrode 12 the operating point of the semiconductor component can be adjusted. In particular, it is therefore not necessary to manufacture the component already with a predetermined barrier height, but the height of the barrier can be suitably adjusted via the control electrode, for example by means of a previously determined predetermined control voltage or a control potential.

If, for example, a positive control voltage V _{S is applied} to the component, then it is possible for there to be between the contact areas 4 . 5 the in 2 B dashed band shown result. The barrier can therefore be lowered, for example.

In particular, a single photon may suffice to produce a significant measurable current signal of the semiconductor component 1 trigger. If the signal is detected, a single photon or even a radiation pulse can be detected efficiently.

Becomes after the signal current flow to the control electrode a suitably poled Voltage applied, for example for holes a negative voltage, so can the charge carriers accumulated in the barrier area are removed from the barrier area ("Sucked off"). As a result, it increases the barrier again. A signal current flow can then be prevented again become. The detector is then in the initial state and ready again for a renewed Radiation detection.

Of the Radiation detector can over the control electrode, in particular from the signal current flow, in one Time interval of 1 ms or less, preferably 1 μs or less, more preferably 50 ns or less, for example 10 ns or less, from 1 ns or less, from 100 ps or less, or from 50 ps or less to the initial state. The Time interval can be between each including 1 ns and 10 ns.

successive Detection operations can accordingly in particular with a frequency of 1 kHz or more, preferably from 50 kHz or more, more preferably 300 kHz or more, for Example of 1 MHz or more, 20 MHz or more, 100 MHz or more, 1 GHz or more, 10 GHz or more, or 20 GHz or more become.

A comparatively time-consuming reset of the semiconductor device 1 in the initial state via quenching as in the avalanche photodiode can be avoided.

The course of the doping profile of the contact area 4 along the current path 6 over the detection area 7 , the barrier area 8th and in particular the blocking area 9 to the contact area 5 is in 2 merely exemplified as nipin. Optionally working components may also be formed with the following doping profiles: pinip, ninip, pipin, pipip or ninin.

Becomes in this case, the barrier area by means of an n-type doped barrier area formed, that would be Role of electrons and holes swapped accordingly. Also the polarity of the applied voltages / potentials would be possible suitable to reverse.

Since the charge carriers generated by impact ionization do not contribute significantly to the signal, the semiconductor device can be operated at significantly lower voltages than an avalanche photodiode. Rather, the signal current can be formed exclusively or predominantly by the current flowing between contact regions, the charge carriers generated by impact ionization essentially serving only for breaking down the potential barrier. In particular, the full amplification factor of the modified transistor underlying the semiconductor component can lead to the signal. The amplification factor can be 10 ⁴ or more, preferably 10 ⁵ or more.

There the impact ionization not the one for the signal current strength authoritative Mechanism is, the semiconductor device can with analog sizing too a given avalanche photodiode compared with the avalanche photodiode with much lower Contact voltages (operating voltages) are operated.

This has a particular advantage in the formation of a semiconductor device with a plurality of such semiconductor devices. Because the Operating voltage (contact voltage) is comparatively low, the Semiconductor devices opposite Avalanche photodiodes are packed more densely and / or an electrical Isolation between adjacent semiconductor devices may be lower, for example thinner, accomplished be without the risk of crosstalk or electrical Punch is increased between adjacent semiconductor devices.

at an increase the packing density of the semiconductor devices becomes that for radiation detection to disposal standing area the semiconductor device and above In particular, the quantum yield per unit area increased.

3 schematically shows a plan view of such a semiconductor device 100 with a plurality of semiconductor devices 1 which are expediently designed and in particular operable as described above. The semiconductor device may be monolithically integrated. A single contact area 5 can all semiconductor devices 1 the semiconductor device 100 to be mean.

The semiconductor devices 1 For example, they may be made from a common epitaxial layer sequence grown on a substrate. The substrate can be the all semiconductor devices 1 the semiconductor device 100 common contact area 5 form.

4 shows a schematic sectional view of an embodiment of a radiation detector 200. , The radiation detector 200. has a semiconductor device 100 or a semiconductor device 1 as described above. Radiation entrance side of the semiconductor device or the semiconductor device is a conversion element 18 upstream.

In the conversion element 18 can radiation 19 whose wavelength is within the spectral sensitivity range of the detection range and therefore can not generate a primary charge carrier in radiation 20 whose wavelength is within the spectral sensitivity range of the detection region and which can therefore generate a primary charge carrier.

The radiation 19 may be, for example, X-rays or γ-radiation. As a conversion element, for example, a scintillator is suitable. This can be radiation 20 within the sensitivity range of the detection region of the semiconductor device 1 or the semiconductor device 100 , which is preferably based on silicon, generate.

The number is in the conversion element 18 generated photons of radiation 20 preferably proportional to the energy of the radiation incident on the conversion element 19 or the energy of the incident radiation quantum. That in the semiconductor device 100 or the semiconductor device 1 The signal obtained is preferably proportional to the number of absorbed photons of the radiation 20 , In this way, an energy-resolved measurement of the incident radiation 19 be achieved.

5 shows a further embodiment of a radiation-receiving semiconductor device 1 using a schematic sectional view. Unlike that related to 1 described semiconductor device, which is designed as a vertical component is the device according to 5 designed as a lateral component. However, the basic structure corresponds to the semiconductor device described above. In contrast, the individual areas, so the contact areas 4 . 5 , the detection area 7 , the barrier area 8th and / or the restricted area 9 laterally next to each other in the semiconductor body 2 arranged and preferably in a semiconductor layer 21 educated. The dielectric layer 14 can for the window 15 be omitted. The anti-reflective coating 16 can in the window 15 be arranged the dielectric layer. The basic mode of operation of the component corresponds to that described above in connection with the other exemplary embodiments.

The semiconductor layer 21 can on a substrate 22 be arranged. Between the substrate 22 and the semiconductor body 2 in the present case by a single semiconductor layer 21 may be formed, an insulating layer 23 be arranged. A prefabricated structure with the substrate 22 the insulation layer 23 and the semiconductor layer 21 For example, it can be purchased as a silicon-on-insulator substrate from SOITEC.

The current path 6 extends laterally along a main lateral extension direction or plane of the semiconductor layer 21 or the substrate 22 , The semiconductor layer 21 can be grown monocrystalline and in particular epitaxially.

The individual doped regions of the semiconductor layer can by means of Implantation of dopants are formed. A lateral Component is opposite a vertical component less expensive in manufacturing. Thus, a lateral component is particularly suitable for mass production.

The insulation layer 23 can the flow of charge carriers from the semiconductor body 2 into the substrate.

The The invention is not by the description based on the embodiments limited. Much more For example, the invention includes every novel feature as well as every combination of features, in particular any combination of features in the claims includes, even if this feature or this combination itself not explicitly stated in the patent claims or exemplary embodiments is.

1

Semiconductor device

2

Semiconductor body

3

Radiation input side

4, 5

electrical contact area

6

electrical current path

7

detection range

8th

barrier region

9

stopband

10 11

electrical connection

12

control electrode

13

control connection

14

dielectric

15

window

16

Antireflection coating

17

Radiation entrance area

18

conversion element

19 20

radiation

21

Semiconductor layer

22

substratum

23

insulation layer

100

A semiconductor device

F

Fermi

V

valence

L

conduction band

P

potential barrier

V _K

Contact voltage

E _p

Primary electron

H _p

Primary hole

E _s

Secondary electron

H _s

Secondary hole

I

signal current

V _S

control voltage

Claims (59)

Radiation-receiving semiconductor device with a semiconductor body and a radiation entrance side, wherein - The semiconductor body one for the Radiation reception provided detection area, at least two electrical contact areas and at least one doped barrier area having, - yourself a current path extends between the contact regions in the semiconductor body, - the barrier area and the detection area in the current path between the contact areas are arranged and - of the Barrier area suitable for forming a potential barrier is that between the detection area and the contact area is arranged, which seen along the current path on the of the detection area facing away from the barrier area is located. Semiconductor component according to Claim 1, which is such is formed, that a primary charge carrier in the Detection area by impact ionization Create secondary carriers can. Semiconductor component according to claim 2, which is designed in this way is that the primary charge carrier by absorption of radiation in the detection area can be generated. Semiconductor component according to at least one of the preceding Claims, which is designed and operable such that a flow of charge carriers, which in the semiconductor body be generated from the detection area through the barrier area in the contact area, which is seen along the current path the side of the barrier area facing away from the detection area is arranged, during operation of the device by means of the potential barrier can be hampered. Semiconductor component according to at least one of the preceding Claims, which is designed and operable in such a way that generated in the semiconductor body charge carrier a first charge carrier type drift to the barrier area, gather in the barrier area and so the height can reduce the potential barrier. Semiconductor component according to Claim 5, which is such is formed and operable, that charge carriers of a second charge carrier type after reducing the potential barrier from the one contact area through the barrier area and the detection area in the other Contact area can flow. Semiconductor component after at least one of the preceding claims, comprising a control electrode for applying an electric control field to the barrier region. A semiconductor device according to claim 7, wherein the control electrode over extends the barrier area. Semiconductor component according to claim 7 or 8, at the height the potential barrier over the control electrode is controllable. Semiconductor component according to one of Claims 7 to 9, in which between the control electrode and the semiconductor body a Dielectric is arranged. Semiconductor component according to at least one of the preceding Claims, when viewed along the current path on the detection area on the opposite side of the barrier region, a blocking region is provided in the semiconductor body is. Semiconductor component according to at least one of the preceding Claims, in which the blocking region is designed in such a way that during operation of the Device tunneling of carriers from the barrier area in the along the current path seen on the from the detection area remote side of the barrier area arranged contact area is avoidable or reducible. Semiconductor component according to one of Claims 7 to 12, wherein the control electrode over one or a plurality the following areas: detection area, restricted area. Semiconductor component according to at least one of the preceding Claims, in which one or a plurality of the following ranges is intrinsically executed: Detection area, restricted area. Semiconductor component according to at least one of the preceding Claims, in which the contact areas are made doped. Semiconductor component according to at least one of the preceding Claims, where the contact areas for are doped to the same type of line. Semiconductor component according to one of Claims 1 to 15, in which the contact areas for different types of lines are doped. Semiconductor component according to one of Claims 1 to 16, where the barrier area for the same type of line is doped like the contact areas. Semiconductor component according to one of Claims 1 to 16, where the barrier area for another line types is doped as the contact areas. Semiconductor component according to at least one of the preceding Claims, in the case of the detection area, the radiation entry side of one of the contact areas is upstream and in this contact area a window for the radiation entry is formed in the detection area. Semiconductor component according to at least one of the preceding Claims, in which the detection area radiation entry side, an anti-reflection layer is upstream. A semiconductor device according to claims 20 and 21, wherein the anti-reflection layer is arranged in the window. Semiconductor component according to at least one of the preceding Claims, in which the barrier area is highly doped. Semiconductor component according to at least one of the preceding claims, in which the barrier region has a dopant concentration of 1 × 10 ¹⁹ l / cm ³ or more. Semiconductor component according to at least one of the preceding claims, in which the barrier region has a dopant concentration of 1 × 10 ²⁰ l / cm ³ or more. A semiconductor device according to at least one of the preceding claims, wherein the barrier region has a dopant concentration of 1 x 10 ²¹ l / cm ³ or more. Semiconductor component according to at least one of the preceding Claims, wherein the barrier region is doped such that a sharp rise formed in the dopant concentration with respect to regions of the semiconductor body is adjacent to the barrier area along the current path. A semiconductor device according to claim 27, wherein the dopant concentration along the current path at the transition from outside of the barrier area into the barrier area or within the barrier area on a distance of 10 nm or less along the current path fivefold or more, preferably seven times or more, more preferably nine times or more, increased. Semiconductor component according to at least one of the preceding claims, in which the Barrier region is doped such that the semiconductor device along the current path has a triangular-shaped potential barrier in the energy band diagram between the contact areas. Semiconductor component according to at least one of the preceding Claims, in which the barrier area, the detection area and preferably the stopband are matched to one another such that the semiconductor device along the current path a triangular shaped potential barrier has in the energy band diagram between the contact areas. Semiconductor component according to at least one of the preceding Claims, where the barrier area along the current path seen a Extension of 20 nm or less, preferably 15 nm or less, particularly preferably 12 nm or less. Semiconductor component according to at least one of the preceding Claims, where the barrier area along the current path seen a Extension of 3 nm or more, preferably 5 nm or more, especially preferably of 10 nm or more. Semiconductor component according to at least one of the preceding Claims, wherein the detection area along the current path is an extension of 100 nm or more, preferably 300 nm or more, especially preferably of 500 nm or more. Semiconductor component according to at least one of the preceding Claims, wherein the detection area along the current path is an extension from between inclusive 100 nm and inclusive 1000 nm, preferably between 200 nm and 900 inclusive nm, more preferably between 300 nm inclusive and 800 inclusive nm. Semiconductor component according to one of Claims 11 to 34, wherein the detection area along the current path an extension which is larger as the extent of the stopband along the current path. Semiconductor component according to at least one of the preceding Claims, that for the detection of a single photon or a radiation pulse suitable and in particular designed. Semiconductor component according to at least one of the preceding Claims, that as a photon counter suitable and in particular designed. Semiconductor component according to at least one of the preceding Claims, in which the semiconductor body based on silicon. Semiconductor component according to at least one of the preceding Claims that designed as a unipolar device is. Semiconductor component according to at least one of the preceding Claims, in which the semiconductor body having one or a plurality of epitaxial layers. Semiconductor component according to at least one of the preceding Claims, which is designed as a vertical component. Semiconductor component according to at least one of the preceding Claims, in which the semiconductor body a semiconductor layer stack, wherein the semiconductor layer stack each a separate layer for one, a plurality or all of the following areas: the one contact area, the other contact area, the barrier area, the detection area, the restricted area. Semiconductor component according to one of Claims 1 to 40, which is formed as a lateral component. A semiconductor device according to claim 43, wherein the Contact areas, the barrier area and the detection area lateral formed side by side in a common semiconductor layer are. Semiconductor component according to at least one of the preceding Claims, which has a substrate on which the semiconductor body is arranged is. Semiconductor component according to one of Claims 43 to 45, in which the detection area is electrically isolated from the substrate is. Semiconductor component according to one of Claims 7 to 46, wherein the device has a modified MOSFET structure, being a contact area for the source, the other contact area for the drain and the control electrode is provided as a gate electrode and wherein the detection area between the barrier area and the drain is arranged. Semiconductor arrangement with a plurality of side by side trained radiation-receiving semiconductor devices according to at least one of the preceding claims, wherein the semiconductor components monolithic integrated running are. Radiation detector with a semiconductor device or a semiconductor device according to at least one of the preceding claims for the detection of radiation outside the spectral sensitivity range of the detection area, wherein the radiation detector comprises a conversion element, the incident radiation into radiation within the spectral sensitivity range the detection area converts. Radiation detector according to claim 49, for detection of X-rays is trained. Use of a semiconductor device, a semiconductor device or a radiation detector according to at least one of the preceding claims for the analysis of Composition of a sample material. Method for operating a radiation-receiving Semiconductor device, a semiconductor device or a radiation detector according to at least one of the preceding claims, comprising the steps: a) Applying a contact voltage between the two contact areas, in which the contact voltage and the detection range so be matched to each other in the detection area by absorption generated charge carriers of a charge carrier type in the detection area by impact ionization additional charge carriers can generate and where the potential barrier formed by the barrier region and the contact voltage are matched to one another such that a signal current flow from one contact region to the other Contact area is prohibited; b) absorption of radiation, in particular a single photon or a radiation pulse, in Detection area to produce at least one primary charge of a Charge carrier type in Detection area by the absorbed radiation; c) production of secondary carriers by impact ionization through the primary charge carrier in the detection area; d) Reduction of the potential barrier by secondary carriers of a charge carrier type, which drift to the barrier area and collect there, thus, a signal stream from one contact area to the other Contact area flows. The method of claim 52, wherein prior to step b) a predetermined control voltage, the formation of a to for signal current flow by means of the secondary charge carrier degradable potential barrier is suitable, determined and applied to the barrier area. A method according to claim 52 or 53, wherein Step d) by applying a suitably poled control voltage At the barrier area, the secondary charge carriers drifted into the barrier area be removed from the barrier area. A method according to any one of claims 52 to 54, wherein the removal of the secondary charge carrier the Procedure with step b) is restarted. A method according to any one of claims 52 to 55, wherein the Contact voltage 75 V or less, preferably 60 V or less, more preferably 50V or less. A method according to any one of claims 52 to 56, wherein the Contact voltage 20 V or more, preferably 30 V or more, especially preferably 40 V or more. A method according to any one of claims 52 to 57, wherein the Control voltage half the contact voltage or less. A method according to any of claims 52 to 58, wherein the Signal current is 0.1 mA or more.