Patent Application
20230420606
This application claims the priority benefit of Taiwan application serial no. 111123986, filed on Jun. 28, 2022. The entirety of the above-mentioned patent application is hereby incorporated by reference herein and made a part of this specification.
The present invention relates to a method for manufacturing a light-absorbing structure, and particularly relates to a method for manufacturing a terahertz (THz) device.
THz has conducted to a great variety of unique applications such as high-speed communication, non-destructive imaging, chemical identification, material characterization, and biomedical sensing. Among various THz emitting and sensing technologies, photoconductive THz devices are widely adopted in THz systems due to their compact size, room temperature operation, and broad bandwidth. Materials for the conventional photoconductive THz devices are mainly based on low-temperature-grown (LT) materials such as LT-GaAs or LT-InGaAs. In general, the LT materials are grown through a molecular beam epitaxy (MBE) process under an ultra-high vacuum environment, such that precise controls for the epitaxial conditions of the MBE process are required to obtain a high-quality structure. As a result, a complex fabrication process and time-consuming nature lead to high manufacturing costs, and thus obstructs THz devices from being mass-produced and fully commercialized.
The present invention provides a method for manufacturing a terahertz (THz) device in which a light-absorbing structure of the THz device is designed to be formed by a chemical vapor deposition (CVD) process, so that the THz device has lower manufacturing costs and production time as compared to the THz device formed by a molecular beam epitaxy (MBE) process and thus is benefit to the mass production and full commercialization. Moreover, the THz device formed by the CVD process has comparable performances (e.g., power or bandwidth performance) as compared to the THz device formed by the MBE process.
An embodiment of the present invention provides a method for manufacturing a THz device, which includes a step of forming a light-absorbing structure on a substrate by using a CVD process. The substrate includes a semiconductor substrate, a sapphire substrate, a quartz substrate, or a combination thereof. The light-absorbing structure includes a semiconductor material, a two-dimensional material, a low-dimensional material, a magnetic material, a topological material, or a combination thereof.
In some embodiments, the CVD process is performed at a pressure ranging from about 10 torr to about 100 torr.
In some embodiments, the substrate is a semiconductor substrate including GaAs, InP, SiC, sapphire, silica, GaN, or Si, and the light-absorbing structure is a semiconductor structure including a III-V compound, a IV element, a IV compound, or a combination thereof.
In some embodiments, the substrate is a semiconductor substrate including GaAs, and the semiconductor structure is a single-laver semiconductor including InGaAs.
In some embodiments, a gas source used in the CVD process includes AsH3, a trimethyl (TMGa), and a trimethyl indium (TMIn).
In some embodiments, the substrate is a semiconductor substrate comprises InP, and the semiconductor structure is a stacked layer including at least one first semiconductor layer and at least one second semiconductor layer. The first semiconductor layer includes InAlAs, and the second semiconductor layer includes InGaAs.
In some embodiments, the at least one first semiconductor layer includes a plurality of first semiconductor layers, and the at least one second semiconductor layer includes second semiconductor layers. The plurality of first semiconductor layers and the plurality of second semiconductor layers are alternately stacked with each other.
In some embodiments, the substrate is a semiconductor substrate including Si, and the semiconductor structure is a stacked layer including a first semiconductor layer and a second semiconductor layer or a single-layer semiconductor including Ge, GeSn, or GaAs. The first semiconductor layer includes Ge, and the second semiconductor layer includes GeSn.
In some embodiments, the first semiconductor layer is formed on the substrate by using a first CVD process, and the second semiconductor layer is formed on the first semiconductor layer by using a second. CVD process. A gas source used in the first CVD process includes H2 and GeH4, and a gas source used in the second CVD process includes Ge4H6 and SnCl4.
In some embodiments, the temperature used in the first CVD process is about 375° C. to about 400° C., and the temperature used in the second CVD process is about 320° C.
Based on the above, in the method for manufacturing the THz device, the light-absorbing structure of the THz device is designed to be formed by the CVD process, so that the THz device has lower manufacturing costs, lower production time, and higher yield as compared to the THz device formed by the MBE process, and thus is benefit to the mass production and full commercialization. Moreover, the THz device formed by the CVD process has comparable performances (e.g., power or bandwidth performance) as compared to the THz device formed by the MBE process.
To make the above features and advantages of the disclosure more comprehensible, several embodiments accompanied with drawings are described in detail as follows.
The accompanying drawings are included to provide a further understanding of the disclosure, and are incorporated in and constitute a part of this specification. The drawings illustrate embodiments of the disclosure and, together with the description, serve to explain the principles of the disclosure.
In the following detailed description, for purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of the disclosed embodiments. It will be apparent, however, that one or more embodiments may be practiced without these specific details. In other instances, well-known structures and devices are schematically shown in order to simplify the drawing.
The invention will be described more comprehensively below with reference to the drawings for the embodiments. However, the invention may also be implemented in different forms rather than being limited by the embodiments described in the invention. Thicknesses of layer and region in the drawings are enlarged for clarity. The same reference numbers are used in the drawings and the description to indicate the same or like parts, which are not repeated in the following embodiments.
It will be understood that when an element is referred to as being “on” or “connected” to another element, it may be directly on or connected to the other element or intervening elements may be present. If an element is referred to as being “directly on” or “directly connected” to another element, there are no intervening elements present. As used herein, “connection” may refer to both physical and/or electrical connections, and “electrical connection” or “coupling” may refer to the presence of other elements between two elements.
As used herein, “about”, “approximately” or “substantially” includes the values as mentioned and the average values within the range of acceptable deviations that can be determined by those of ordinary skill in the art. Consider to the specific amount of errors related to the measurements (i.e., the limitations of the measurement system), the meaning of “about” may be, for example, referred to a value within one or more standard deviations of the value, or within ±30%, ±20%, ±10%, ±5%. Further ore, the “about”, “approximate” or “substantially” used herein may be based on the optical property, etching property or other properties to select a more acceptable deviation range or standard deviation, but may not apply one standard deviation to all properties. The terms used herein are used to merely describe exemplary embodiments and are not used to limit the present disclosure. In this case, unless indicated in the context specifically otherwise the singular forms include the plural forms.
Referring to
In some embodiments, the light-absorbing structure 110 may be formed by depositing a semiconductor material through the CVD process at a pressure ranging from about 10 torr to about 100 torr. As such, the required equipment and time to achieve an ultra-high vacuum environment can be omitted as compared to the MBE growth process being performed in the ultra-high vacuum environment (e.g., 10−9 torr), and thus the manufacturing costs and production time for the THz device 10 can be decreased significantly and the yield for the THz device 10 can be increased. In some embodiments, in the case where the light-absorbing structure 110 is a semiconductor structure, the THz device 10 formed by the above CVD process have a resistivity ranging from about 10k ohm/sq to about 100M ohm/sq, a carrier mobility ranging from about 100 cm2/V−s to about 2000 cm2/V−s, and a carder lifetime ranging from about 1 ps to about 500 ps. Based on the above, the THz device formed by the CVD process has lower manufacturing costs, lower production time and higher yield as compared to the THz device formed by the MBE process and thus is benefit to the mass production and full commercialization. Moreover, the THz device formed by the CVD process has comparable performances (e.g., power or bandwidth performance) as compared to the device formed by the MBE process. In some embodiments, the CVD process is performed by controlling the temperature of the substrate at about 400° C. to about 800° C.
In some embodiments, the above CVD process may include a metal-organic CVD (MOCVD), a plasma-enhanced CVD (PECVD), a remote plasma-enhanced CVD (RPECVD), a reduced-pressure CVD (RPCVD), an atmospheric pressure CVD (APCVD), a low-pressure CVD (LPCVD), an aerosol assisted CVD (AACVD), a direct liquid injection CVD (DLICVD), a microwave plasma-assisted CVD (MPCVD), an atomic layer CVD (ALCVD), a hot wire CVD (HWCVD), a hot filament CVD (HFCVD), a hybrid physical-chemical vapor deposition (HPCVD), a rapid thermal CVD (RTCVD), or a combination thereof.
In some embodiments, the substrate 100 is a semiconductor substrate including GaAs, InP, or Si, and the light-absorbing structure 110 is a semiconductor structure including a III-V compound, a IV element, a IV compound, or a combination thereof. In some embodiments, the substrate is a semiconductor substrate including GaAs, and the semiconductor structure is a single-layer semiconductor including InGaAs. In some embodiments, in the case where the semiconductor structure is the single-layer semiconductor including InGaAs, a gas source used in the CVD process includes AsH3, trimethyl gallium (TMGa), and trimethyl indium (TMIn). In some embodiments, the molar ratio of In, Ga and As in InGaAs may be 0.2:0.8:1 (which may be expressed as In0.2Ga0.8As).
In some embodiments, dopants may be doped in the semiconductor structure through a doping process to further increase the resistivity of the semiconductor material and obtain a shorter lifetime carrier cycle, which is benefit to improve the power and bandwidth performance of the THz device. For example, elements such as Be, C, Au, Rh, Er, or Fe may be doped in the semiconductor structure. In some embodiments, in the case where the light-absorbing structure 110 is a semiconductor structure including the III-V compound such as InGaAs or InAlAs, the elements such as Be can be doped in the semiconductor structure.
Referring to a result shown in
Moreover, as compared to the THz device formed by the MBE growth process, the manufacturing costs and production time for the THz device 10 can be decreased significantly and the yield for the THz device 10 can be increased. For example, the CVD process is performed at a pressure raging from about 10 torr to about 100 ton, which can omit the required equipment and time to achieve an ultra-high vacuum environment as compared to the MBE growth process being performed in the ultra-high vacuum environment 10−9 torr). In some alternative embodiments, the CVD process is performed at a pressure raging from about 37 torr to about 75 torr.
Referring to a result shown in
In some embodiments, in the case where the substrate 100 is a semiconductor substrate including GaAs and the light-absorbing structure 110 is a semiconductor structure including a single-layer semiconductor including InGaAs, the central wavelength range of the femtosecond laser used for the THz device 10 is about 500 nm to about 1600 nm. In some embodiments, the thickness of the single-layer semiconductor is about 10 μm to about 2 μm.
Referring to
Referring to
Referring to
In some embodiments, in the case where the substrate 400 is a semiconductor substrate including Si, the first semiconductor layer 412 includes Ge, and the second semiconductor layer 414 includes GeSn, the THz device 40 has a bandwidth exceeding 2 THz and a SNR more than 50 dB under the excitation of a femtosecond laser with a central wavelength of 1560 nm (e.g., Example 3 shown in
The first semiconductor layer 412 may be formed on the substrate 400 by using a first CVD process, and the second semiconductor layer 414 may be formed on the first semiconductor layer 412 by using a second CVD process. In some embodiments, in the case where the first semiconductor layer 412 includes Ge and the second semiconductor layer 414 includes GeSn, a gas source used in the first CVD process includes H2 and GeH4, and a gas source used in the second CVD process includes Ge2H6 and SnCl4. In some embodiments, in the case where the second semiconductor layer 414 is formed by the above second CVD process, the molar ratio of Ge and Sn in GeSn may be 0.96:0.04 (which may be expressed as Ge0.96Sn0.04). In some embodiments, the first CVD process is performed by controlling the temperature of the substrate at about 375° C. to about 400° C. In some embodiments, the second CVD process is performed by controlling the temperature of the substrate at about 320° C. The thickness of the first semiconductor layer 412 and/or the second semiconductor layer 414 is about 10 nm to about 2 μm. For example, the thickness of the first semiconductor layer 412 is about 120 nm, and the thickness of the second semiconductor layer 414 is about 150 nm.
Based on the above, in the method for manufacturing the THz device, the light-absorbing structure of the THz device is designed to be formed by the CVD process, so that the THz device has lower manufacturing costs, lower production time, and higher yield as compared to the THz device formed by the MBE process and thus is benefit to the mass production and full commercialization. Moreover, the performance such as power or bandwidth performance of the THz device formed by the CVD process are comparable to that of the THz device formed by the MBE process.
It will be apparent to those skilled in the art that various modifications and variations can be made to the disclosed embodiments. It is intended that the specification and examples be considered as exemplary only, with a true scope of the disclosure being indicated by the following claims and their equivalents
| Number | Date | Country | Kind |
|---|---|---|---|
| 111123986 | Jun 2022 | TW | national |
