Recently, the Micro-Nano Manufacturing and System Integration Research Center of Chongqing Institute of Green and Intelligent Technology published a paper titled “An All-in-One Optoelectronic Logic Device with Self-Distinguishable Dual-Band Photoresponse” in Device, a journal of the Cell Press. In this paper, an all-in-one optoelectronic logic device with self-distinguishable dual-band photoresponse is proposed. This device can distinguish the band of incident light, by exploiting its tunable bi-directional photocurrents (i.e., positive and negative photocurrent) in ultraviolet and near-infrared bands. This feature greatly enhances the flexibility of optical modulation on device electrical signals, enabling the device to achieve three logical states and five basic logical operations. The research results provide vital references for the development of highly integrated and multifunctional optoelectronic logic devices.
Figure 1. Schematic diagram of implementing optoelectronic logic operations using the optoelectronic logic device with self-distinguishable response band.
Electronic-based logic operations are the foundation of modern computer processing systems. However, with the downscaling of semiconductor integrated circuits, issues such as interconnect crosstalk and resistive Joule heating become increasingly serious. In recent years, the introduction of optoelectronic logic operations provide new insights for addressing the challenges faced by electronic logic operations. Signal transmission enabled by photons can effectively reduce crosstalk and eliminate the impact of Joule heating caused by resistance in circuit interconnects.
As the core of optoelectronic logic operations, photodetectors are capable of converting optical signals into electrical signals, which can further be used to obtain processable digital signals. Traditional photodetectors typically exhibit an uni-directional photocurrent, which makes the corresponding optoelectronic logic devices only capable of implementing a single logic function, or require additional circuit layouts to expand their logic function. To address this challenge, members of the Micro-Nano Manufacturing and System Integration Research Center propose an optoelectronic logic device structure with self-distinguishable response band. The device can achieve bi-directional photocurrents related to the incident light bands and perform multiple logic operations in a single unit (Figure 1).
To accurately characterize the bi-directional photoresponse performance of this optoelectronic logic device, ultraviolet (375 nm) and near-infrared (1550 nm) lasers were used to irradiate the device in sequence, and the output photocurrent was recorded. According to the test results, it can be seen that when the incident light wavelength changes from 375 nm to 1550 nm, the direction of the photocurrent changes from “positive” to “negative”. The responsivity of the device under 375 nm and 1550 nm illumination reaches +104 A/W and -800 A/W, respectively (Figure 2), indicating that the device can efficiently convert optical signals into electrical signals.
Figure 2. Bi-directional photoresponse of the optoelectronic logic device with self-distinguishable response band. (a) Schematic diagram of the testing process for bi-directional photoresponse. (b) I-T curves of the device under ultraviolet and near-infrared illuminations. Insert: I-V curve in the dark state. (c, d) Photocurrent and responsivity under ultraviolet and near-infrared illuminations with different power densityies.
A demonstration system centered on this device was established, including an ultraviolet (UV) light source, a near-infrared (NIR) light source, a signal sampling circuit, a host computer, and a bi-color light-emitting diode (LED) (Figure 3). When UV light is incident, the bi-color LED emits blue light; when NIR light is incident, the bi-color LED emits green light; and when no light is incident, the bi-color LED does not emit light. The three states of the LED, namely no light, blue light, and green light, correspond to the three logic states of “0”, “1”, and “-1”, respectively.
Figure 3. Implementation of three logic states using the optoelectronic logic device with self-distinguishable response band.
Furthermore, this optoelectronic logic device is capable of executing five fundamental logic functions: “AND”, “OR”, “NOT”, “NAND”, and “NOR”. It is worth emphasizing that this method of using modulation light to switch logical functions has the advantages of reversibility and reproducibility. Additionally, this method does not rely on complex external circuit designs, providing an efficient and subtle solution for realizing multiple optoelectronic logic operations in a single device.
The first author is Jintao Fu, a doctoral student from the the Micro-Nano Manufacturing and System Integration Research Center, and Professor Xingzhan Wei is the corresponding author.
Link to relevant paper:
https://www.cell.com/device/fulltext/S2666-9986(24)00113-3