Classifications

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  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10D—INORGANIC ELECTRIC SEMICONDUCTOR DEVICES
  • H10D8/00—Diodes
  • H10D8/01—Manufacture or treatment
  • H10D8/045—Manufacture or treatment of PN junction diodes
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  • H10F—INORGANIC SEMICONDUCTOR DEVICES SENSITIVE TO INFRARED RADIATION, LIGHT, ELECTROMAGNETIC RADIATION OF SHORTER WAVELENGTH OR CORPUSCULAR RADIATION
  • H10F10/00—Individual photovoltaic cells, e.g. solar cells
  • H10F10/10—Individual photovoltaic cells, e.g. solar cells having potential barriers
  • H10F10/16—Photovoltaic cells having only PN heterojunction potential barriers
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  • H10F30/00—Individual radiation-sensitive semiconductor devices in which radiation controls the flow of current through the devices, e.g. photodetectors
  • H10F30/20—Individual radiation-sensitive semiconductor devices in which radiation controls the flow of current through the devices, e.g. photodetectors the devices having potential barriers, e.g. phototransistors
  • H10F30/21—Individual radiation-sensitive semiconductor devices in which radiation controls the flow of current through the devices, e.g. photodetectors the devices having potential barriers, e.g. phototransistors the devices being sensitive to infrared, visible or ultraviolet radiation
  • H10F30/22—Individual radiation-sensitive semiconductor devices in which radiation controls the flow of current through the devices, e.g. photodetectors the devices having potential barriers, e.g. phototransistors the devices being sensitive to infrared, visible or ultraviolet radiation the devices having only one potential barrier, e.g. photodiodes
  • H10F30/222—Individual radiation-sensitive semiconductor devices in which radiation controls the flow of current through the devices, e.g. photodetectors the devices having potential barriers, e.g. phototransistors the devices being sensitive to infrared, visible or ultraviolet radiation the devices having only one potential barrier, e.g. photodiodes the potential barrier being a PN heterojunction
• • H—ELECTRICITY
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  • H10F—INORGANIC SEMICONDUCTOR DEVICES SENSITIVE TO INFRARED RADIATION, LIGHT, ELECTROMAGNETIC RADIATION OF SHORTER WAVELENGTH OR CORPUSCULAR RADIATION
  • H10F71/00—Manufacture or treatment of devices covered by this subclass
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  • H10F—INORGANIC SEMICONDUCTOR DEVICES SENSITIVE TO INFRARED RADIATION, LIGHT, ELECTROMAGNETIC RADIATION OF SHORTER WAVELENGTH OR CORPUSCULAR RADIATION
  • H10F77/00—Constructional details of devices covered by this subclass
  • H10F77/20—Electrodes
  • H10F77/206—Electrodes for devices having potential barriers
• • H—ELECTRICITY
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  • H10P—GENERIC PROCESSES OR APPARATUS FOR THE MANUFACTURE OR TREATMENT OF DEVICES COVERED BY CLASS H10
  • H10P14/00—Formation of materials, e.g. in the shape of layers or pillars
  • H10P14/20—Formation of materials, e.g. in the shape of layers or pillars of semiconductor materials
  • H10P14/24—Formation of materials, e.g. in the shape of layers or pillars of semiconductor materials using chemical vapour deposition [CVD]
• • H—ELECTRICITY
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  • H10P—GENERIC PROCESSES OR APPARATUS FOR THE MANUFACTURE OR TREATMENT OF DEVICES COVERED BY CLASS H10
  • H10P14/00—Formation of materials, e.g. in the shape of layers or pillars
  • H10P14/20—Formation of materials, e.g. in the shape of layers or pillars of semiconductor materials
  • H10P14/29—Formation of materials, e.g. in the shape of layers or pillars of semiconductor materials characterised by the substrates
  • H10P14/2901—Materials
  • H10P14/2907—Materials being Group IIIA-VA materials
  • H10P14/2912—Antimonides
• • H—ELECTRICITY
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  • H10P—GENERIC PROCESSES OR APPARATUS FOR THE MANUFACTURE OR TREATMENT OF DEVICES COVERED BY CLASS H10
  • H10P14/00—Formation of materials, e.g. in the shape of layers or pillars
  • H10P14/20—Formation of materials, e.g. in the shape of layers or pillars of semiconductor materials
  • H10P14/32—Formation of materials, e.g. in the shape of layers or pillars of semiconductor materials characterised by intermediate layers between substrates and deposited layers
  • H10P14/3202—Materials thereof
  • H10P14/3238—Materials thereof being insulating materials
• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10P—GENERIC PROCESSES OR APPARATUS FOR THE MANUFACTURE OR TREATMENT OF DEVICES COVERED BY CLASS H10
  • H10P14/00—Formation of materials, e.g. in the shape of layers or pillars
  • H10P14/20—Formation of materials, e.g. in the shape of layers or pillars of semiconductor materials
  • H10P14/34—Deposited materials, e.g. layers
  • H10P14/3402—Deposited materials, e.g. layers characterised by the chemical composition
  • H10P14/3414—Deposited materials, e.g. layers characterised by the chemical composition being group IIIA-VIA materials
  • H10P14/3422—Antimonides
• • H—ELECTRICITY
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  • H10P—GENERIC PROCESSES OR APPARATUS FOR THE MANUFACTURE OR TREATMENT OF DEVICES COVERED BY CLASS H10
  • H10P14/00—Formation of materials, e.g. in the shape of layers or pillars
  • H10P14/20—Formation of materials, e.g. in the shape of layers or pillars of semiconductor materials
  • H10P14/34—Deposited materials, e.g. layers
  • H10P14/3402—Deposited materials, e.g. layers characterised by the chemical composition
  • H10P14/3424—Deposited materials, e.g. layers characterised by the chemical composition being Group IIB-VIA materials
  • H10P14/3426—Oxides
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  • H10P—GENERIC PROCESSES OR APPARATUS FOR THE MANUFACTURE OR TREATMENT OF DEVICES COVERED BY CLASS H10
  • H10P14/00—Formation of materials, e.g. in the shape of layers or pillars
  • H10P14/60—Formation of materials, e.g. in the shape of layers or pillars of insulating materials
  • H10P14/63—Formation of materials, e.g. in the shape of layers or pillars of insulating materials characterised by the formation processes
  • H10P14/6326—Deposition processes
  • H10P14/6328—Deposition from the gas or vapour phase
  • H10P14/6334—Deposition from the gas or vapour phase using decomposition or reaction of gaseous or vapour phase compounds, i.e. chemical vapour deposition
  • H10P14/6339—Deposition from the gas or vapour phase using decomposition or reaction of gaseous or vapour phase compounds, i.e. chemical vapour deposition deposition by cyclic CVD, e.g. ALD, ALE or pulsed CVD
• • H—ELECTRICITY
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  • H10P—GENERIC PROCESSES OR APPARATUS FOR THE MANUFACTURE OR TREATMENT OF DEVICES COVERED BY CLASS H10
  • H10P14/00—Formation of materials, e.g. in the shape of layers or pillars
  • H10P14/60—Formation of materials, e.g. in the shape of layers or pillars of insulating materials
  • H10P14/69—Inorganic materials
  • H10P14/692—Inorganic materials composed of oxides, glassy oxides or oxide-based glasses
  • H10P14/6938—Inorganic materials composed of oxides, glassy oxides or oxide-based glasses the material containing at least one metal element, e.g. metal oxides, metal oxynitrides or metal oxycarbides
  • H10P14/6939—Inorganic materials composed of oxides, glassy oxides or oxide-based glasses the material containing at least one metal element, e.g. metal oxides, metal oxynitrides or metal oxycarbides characterised by the metal
  • H10P14/69391—Inorganic materials composed of oxides, glassy oxides or oxide-based glasses the material containing at least one metal element, e.g. metal oxides, metal oxynitrides or metal oxycarbides characterised by the metal the material containing aluminium, e.g. Al2O3

Definitions

• the present invention relates generally to a method, apparatus for fabricating a diode with a narrow bandgap semiconductor operating with rectifying properties at room temperature. More particularly, the present invention relates to a heterojunction narrow bandgap diode and a method of fabrication therefor.
• a junction diode is a fundamental semiconductor device which presents low impedance for polarization above a threshold voltage in forward polarization (i.e. positive voltage applied to p-type semiconductor and negative voltage applied to n-type semiconductor), typically 0.6 V for silicon p-n diodes, and a much higher impedance in reverse polarization.
• a threshold voltage in forward polarization i.e. positive voltage applied to p-type semiconductor and negative voltage applied to n-type semiconductor
• silicon p-n diodes typically 0.6 V for silicon p-n diodes
• an ideal diode is an electrical conductor in one direction of current flow and an insulator in the opposite direction.
• a photodetector diode is a diode which is conduction sensitive to light absorption. Photodetector diodes are constructed for response to light of specific ranges of wavelengths, including but not limited to visible, ultraviolet, and infrared. For example, x-ray detector and gamma-ray detector diodes conduct upon detecting other high-energy photons.
• a band gap also called an energy gap or bandgap
• the band gap In graphs of the electronic band structure of solids, the band gap generally refers to the energy difference (in electron volts "eV") between the top of the valence band and the bottom of the conduction band in insulators and semiconductors.
• Bandgap is the minimum energy required to promote a valence electron bound to an atom in a solid to become a conduction electron, which is free to move within the crystal lattice and serve as a charge carrier to conduct electric current.
• Embodiments of the present invention provide a method, device and photo-detector system.
• An embodiment of the present invention takes the form of a semiconductor device which includes: an n-type doped Zinc Oxide layer and a p-type layer formed of a narrow bandgap material of elements from columns 3A and 5A of the periodical table; and, a junction between the n-type layer and the p-type layer, the junction being operable as a heterojunction diode having a rectifying property at a temperature range, the temperature range having a high limit at room temperature, thereby providing a heterojunction diode that is operable at room temperature.
• the element of group 3A may be Indium
• the element of group 5A may be Antimony.
• the embodiment provides specific types of materials for the heterojunction diode that is operable at room temperature.
• the narrow bandgap material may comprise Indium antimonide (InSb).
• the p-type layer may comprise a single crystal of the narrow bandgap material.
• the n-type layer may comprise Zinc Oxide doped with Aluminum.
• An embodiment of the present invention further includes a window structure, wherein the window structure allows light to reach the n-type layer thereby providing additional structures for the heterojunction diode to be usable for photo-detection.
• An embodiment of the present invention includes a fabrication method for fabricating the semiconductor device.
• Figure 1 depicts an energy band diagram of a semiconductor
• Figure 2 depicts an energy band diagram for a photo-detector
• Figure 3 depicts a block diagram schematic of an example diode formed using the p-n junction embodying the present invention
• Figure 4 depicts a schematic block diagram of an example implementation of a heterojunction narrow bandgap photodetector diode embodying the present invention that can be operated at room temperature in accordance with an illustrative embodiment
• Figure 5 depicts a schematic block diagram of another example implementation of a heterojunction narrow bandgap photodetector diode
• Figure 6 depicts energy band diagram of the heterojunction formed by Al doped ZnO and p-type InSb at room temperature and in equilibrium in accordance with an embodiment of the present invention
• Figure 7 depicts a graph of an operation of a heterojunction diode embodying the present invention.
• Figure 8 a flowchart of an example process for fabricating a heterojunction narrow bandgap diode embodying the present invention that exhibits photo-detection performance at room temperature.
• Figure 1 depicts a simplified chart illustrating bandgap.
• Ev is the maximum energy level of the valence band of a material
• Ec is the minimum energy level of the conduction band of the same material
• Eg is the energy gap - i.e., the bandgap energy - for an electron from the valence band to jump to the conduction band to make the material electrically conducting.
• Figure 2 depicts a chart of a photo-excited transition of the bandgap. An electron can jump from the valence band to the conduction band when the material is exposed to photons whose energy exceeds the bandgap Eg.
• Diodes with narrow bandgap are desirable for long wavelength light, e.g., greater than 1 micron.
• a narrow bandgap is defined as less than 1 eV.
• a bandgap that is not narrow is a large or high bandgap.
• the narrower the bandgap the less the energy required for the material to become conducting. In case of photo-detecting diodes, the narrower the bandgap the less energetic the photons are needed to trigger the diode into conduction.
• Some narrow bandgap photo-detecting diodes are presently available.
• the presently available photodetector diodes with a narrow bandgap are difficult to use because they require cooling to liquid nitrogen temperatures 77 Kelvin or -196 degrees Celsius (°C)) for those diodes to reduce thermal carrier generation, and thus increase signal to noise ratio.
• a diode comprises an electrical junction between a n-type material (also referred to n-doped material) and a p-type material (also referred to as p-doped material).
• the junction is referred to as a p-n junction.
• Embodiments of the present invention provides a p-n diode with a narrow bandgap semiconductor can present rectifier properties at room temperature, which enables detection of photons of long wavelengths at room temperature or without needing cooling to very low temperatures.
• Embodiments of the present invention therefore generally address and solve the above-described need for a heterojunction narrow bandgap diode to operate at low temperatures.
• Embodiments of the present invention also provide a fabrication method for a heterojunction diode employing a narrow bandgap semiconductor that presents a rectifier property at room temperature.
• An apparatus embodying the present invention is a heterojunction diode formed by a large bandgap and a narrow bandgap semiconductor that can operate at room temperature and below.
• Another embodiment of the present invention is a fabrication method for the apparatus.
• An embodiment of the present invention can be configured as a modification of an existing semiconductor fabrication system - such as a photolithography system, as a separate application that operates in conjunction with an existing semiconductor fabrication system, a standalone application, or some combination thereof.
• the application causes the semiconductor fabrication system to perform the steps of a method described herein, to fabricate a heterojunction narrow bandgap diode that can operate at room temperature, as described herein.
• FIG. 1 simplified diagrams of a p-n junction are used in the figures.
• additional structures that are not shown or described herein, or structures different from those shown and described herein, may be present without departing the scope of the present invention.
• a shown or described structure in the example semiconductor device may be fabricated from the same materials but using different methodologies to yield a similar operation or result as described herein.
• Differently shaded portions in the two-dimensional drawing of the example structures, layers, and formations are intended to represent different structures, layers, and formations in the example fabrication, as described herein.
• the different structures, layers, and formations may be fabricated using the described materials or other suitable equivalents of the described materials so long as the equivalent materials exhibit the same or similar properties of the materials, the resulting device, or both, as described herein.
• a specific shape, location, position, or dimension of a shape depicted herein is not intended to be limiting on embodiments of the present invention unless such a characteristic is expressly described as a feature of an embodiment of the present invention.
• the shape, location, position, dimension, or some combination thereof, are chosen only for the clarity of the drawings and the description and may have been exaggerated, minimized, or otherwise changed from actual shape, location, position, or dimension that might be used in actual photolithography to achieve an objective according to embodiments of the present invention.
• embodiments of the present invention are described with respect to specific actual or hypothetical semiconductor devices only as an examples.
• the steps described herein can be adapted for fabricating a variety of planar and non-planar semiconductor devices in a similar manner, and such adaptations are contemplated within the scope of the present invention.
• the specific contacts placements are also used only as examples to describe various operations of embodiments of the present invention.
• Those of ordinary skill in the art will be able to use an embodiment of the present invention to similarly provide electrical access to the p-n junction for other purposes in other manners, and such adaptations are also contemplated within the scope of the present invention.
• An embodiment of the present invention when implemented in an application causes a fabrication process to perform certain steps as described herein.
• the steps of the fabrication process are depicted in the several figures. Not all steps may be necessary in a particular fabrication process. Some fabrication processes may implement the steps in different order, combine certain steps, remove or replace certain steps, or perform some combination of these and other manipulations of steps, without departing the scope of the present invention.
• a method of an embodiment of the present invention described herein, when implemented to execute on a device or data processing system, comprises substantial advancement of the functionality of that device or data processing system in fabricating a heterojunction narrow bandgap photodetector diode that can operate at room temperature and below.
• a substantial advancement of such devices or data processing systems by executing a method of an embodiment of the present invention is in an improved fabrication of a heterojunction with a narrow bandgap semiconductor with rectifying properties at room temperature and below.
• Embodiments of the present invention are described with respect to certain types of devices, electrical properties, structures, formations, layers orientations, directions, steps, operations, planes, structures, dimensions, numerosity, data processing systems, environments, components, and applications only as examples. Any specific manifestations of these and other similar artifacts are not intended to be limiting to the invention. Any suitable manifestation of these and other similar artifacts can be selected within the scope of the present invention.
• embodiments of the present invention may be implemented with respect to any type of data, data source, or access to a data source over a data network.
• Any type of data storage device may provide the data to an embodiment of the invention, either locally at a data processing system or over a data network, within the scope of the invention.
• any type of data storage device suitable for use with the mobile device may provide the data to such embodiment, either locally at the mobile device or over a data network, within the scope of the present invention.
• Embodiments of the present invention are described using specific code, designs, architectures, protocols, layouts, schematics, and tools only as examples and are not limiting to the present invention. Furthermore, the embodiments of the present invention are described in some instances using particular software, tools, and data processing environments only as an example for the clarity of the description. Embodiments of the present invention may be used in conjunction with other comparable or similarly purposed structures, systems, applications, or architectures. For example, other comparable mobile devices, structures, systems, applications, or architectures therefor, may be used in conjunction with such embodiment of the invention within the scope of the invention. An embodiment of the present invention may be implemented in hardware, software, or a combination thereof.
• Diode 300 includes p-n junction 302.
• Junction 302 is formed using Aluminum doped Zinc Oxide (ZnO:AI or AZO) as n-type semiconductor material 304 and Indium antimonide (InSb) as p-type semiconductor material 306.
• Indium is a group 3A element in the periodic table
• Antimony is a group 5A element in the periodic table.
• Other alloys comprising groups 2B and/or 3A and groups 5A and/or 6A elements can also be formed to exhibit behavior similar to that of InSb described herein.
• AZO was chosen because it is transparent to visible and to infrared light and has a higher band gap to allow the formation of a heterojunction.
• junction 302 The specific manner in which materials 304 and 306 are constructed to form junction 302 is
• junction 302 is within the scope of the present invention even if (i) material 304 (or 306) is embedded, infused, doped, or otherwise mixed with other materials; (ii) additional structures, layers, materials are formed or used at or adjacent to junction 302; (iii) additional structures, layers, materials are formed or used on other sides other than the sides of material 304 (or 306) facing junction 302; or some combination thereof.
• this figure depicts a schematic block diagram of an example implementation of a heterojunction narrow bandgap photodetector diode that can be operated at room temperature.
• Semiconductor device 400 is a more detailed example of diode 300 in Figure 3.
• Semiconductor device 400 comprises layer 404 which includes ZnO doped with Aluminum (Al).
• layer 404 includes ZnO doped with Aluminum (Al).
• Al Aluminum
• One non-limiting example method of doping ZnO with Al is using atomic layer deposition (ALD) methodology.
• Material 406 includes InSb, doped with acceptor dopants like Be, Zn, or Cd.
• Junction 402 is an example of junction 302 in Figure 3. Junction 402 can be a formed by electrically bonding a surface of material 404 directly to a surface of material 406 to one another, as an alternative approach.
• a layer of a suitable material 408, e.g., Aluminum Oxide (AI2O3), can also be deposited at junction 402, e.g., using ALD, as an intervening layer between materials 404 and 406 to improve surface passivation of material 406 and thus improving the rectifying properties of the diode.
• a suitable material 408 e.g., Aluminum Oxide (AI2O3)
• ALD atomic layer deposition
• Layers 410 and 412 are optionally fabricated to enable contact placements.
• the contacts (not shown) placed on layers 410 and 412 are usable for electrically connecting semiconductor device 400 with other components in an electrical circuit.
• Layers 410 and 412 can be formed of any material or materials suitable for this purpose, and by using any suitable fabrication methodology. As some non-limiting examples, layer 410 is shown to be fabricated using Al, and layer 412 is shown as fabricated using a bi-layer comprising Chromium (Cr) and Gold (Au).
• FIG. 5 depicts a schematic block diagram of another implementation of a heterojunction narrow bandgap photodetector diode embodying the present invention that can be operated at room temperature.
• Semiconductor device 500 is an example of device 400 in Figure 4, with a modification.
• layer 410 is formed in a manner so as to create window 502.
• window 502 is a suitable structure or an absence thereof, which allows light to reach layer 404.
• window 502 is simply a gap in layer 410, through which light can pass and reach layer 406.
• this figure depicts a likely energy band diagram of the heterojunction formed by Al doped ZnO and p-type InSb at room temperature and in equilibrium (layer 408 is not present).
• An implementation of semiconductor device 400 or 500 was used in depicted plot 600.
• this figure depicts a graph of an operation of a heterojunction diode embodying the present invention at room temperature.
• An implementation of semiconductor device 400 or 500 was used in the measurements taken at room temperature in the dark which are shown in plots 700.
• Plot 700 shows that semiconductor device 400 or 500 exhibits rectifying diode behavior.
• the leakage current current through the device when the device is reversed polarized (i.e. positive voltage applied to n-type material) is also low for the narrow bandgap InSb diode.
• Measurements performed at room temperature for plot 702, in the dark and under illumination with visible light show desirable narrow bandgap photo-detection properties of device 400 or 500 using InSb as p-type material in layer 406.
• That photo-detection would extend to longer wavelengths in the infrared region of spectrum, considering the narrow bandgap energy of the InSb.
• the specific implementations and measurements depicted in Figure 7 are not intended to be limiting on the present invention. Different measurements may be achieved with implementation-specific variations of an embodiment of the present invention, but when layer 406 is configured with InSb as described herein, even the implementation-specific variations should exhibit room temperature narrow bandgap photo-detection performance comparable to that depicted in Figures 6 and 7 within industry-accepted tolerances.
• FIG. 8 depicts a flowchart of an example process embodying the present invention for fabricating a heterojunction narrow bandgap diode that exhibits photo-detection performance at room temperature.
• Process 800 can be implemented as a method of fabrication that operates in conjunction with semiconductor fabrication system.
• a p-type InSb wafer is cleaned to remove organic contamination (block 802).
• Al doped Zinc oxide is deposited (block 806).
• AZO can also be deposited by sputtering.
• the ALD temperature could be in the range from 100C to 300C, the preferred temperature is 180C.
• the thickness is not critical, and can be any thickness greater than 10nm and less than few microns because the layer has to be transparent to visible and infrared light.
• Photolithography process is done to define the AZO area and followed by AZO etch and wafer cleaning (block 808). Photolithography process is done to define the area for contact to n-type semiconductor (block 810).
• Aluminum thin film is deposited by thermal evaporation for contact to AZO (block 812).
• Alternative methods for thin film deposition include electron beam evaporation or sputter deposition.
• Al thickness is preferably in the range of 50 to 500nm.
• the aluminum is lifted-off and wafer cleaning is performed (block 814).
• Backside of wafer is metallized (block 816). Process 800 ends thereafter.
• the metallization of block 816 can be performed with Cr followed by Au for ohmic contact to p-type InSb. Chromium thickness is preferably 10nm and Au thickness is preferably 50nm. Cr is used to enhance Au adhesion. Au thickness is not critical and can be much thicker.

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