Piezotronics and piezophototronics are emerging fields by coupling piezoelectric, semiconductor, and photon excitation effects for achieving high-performance strain-gated sensors, LEDs, and solar cells. The built-in piezoelectric potential effectively controls carrier transport characteristics in piezoelectric semiconductor materials, such as ZnO, GaN, InN, CdS, and monolayer MoS. In this paper, a topological insulator piezotronic transistor is investigated theoretically based on a HgTe/CdTe quantum well. The conductance, ON/OFF ratio, and density of states have been studied at various strains for the topological insulator piezotronic transistor. The ON/OFF ratio of conductance can reach up to 10 with applied strain. The properties of the topological insulator are modulated by piezoelectric potential, which is the result of the piezotronic effect on quantum states. The principle provides a method for developing high-performance piezotronic devices based on a topological insulator.

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Piezotronics and piezo-phototronics have received increasing attention in flexible energy-harvesting devices, self-powered sensor systems utilizing piezoelectric semiconductor materials, such as ZnO, GaN and monolayer MoS 2. Piezoelectric potentials induced by the externally applied strain can effectively control the generation, recombination and transport of the charge carriers for achieving high-performance devices. In this study, we describe the piezotronics effect on the GaN/InN/GaN quantum well, which can induce performances resembling those of topological insulators by a piezoelectric field polarized under the externally applied mechanical strain. The transport properties of bulk and edge states of this quantum well device have been investigated by calculating the electron density distribution 1 These authors contributed equally to this work. 2 under different widths of the quantum point contact (QPC), which is the origin of more conductance plateaus. In addition, we postulate the mechanical-electronic logic operation mechanisms based on the piezotronics effect adjusting the transport of edge states in the quantum well device. Fundamental logic units such as NOT, NAND and NOR gates have been innovatively designed for performing the logic computation functions from external mechanical stimuli. The logic nanodevices based on the topological insulator have near zeropower consumption and ultrahigh ON/OFF ratio. This work provides a deep insight into the piezotronics effect on the transport of bulk and edge states of the quantum well device, and offers novel solutions to design high-performance low-power mechanical-electronic logic devices.

2018). Ultra-high sensitivity strain sensor based on piezotronic bipolar transistor. Nano Energy, 50,[744][745][746][747][748][749] http://dx.

Piezo-phototronics is an emerging field which involves the coupling between photoexcitation, piezoelectricity, and semiconductor. The piezoelectric semiconductors have a non-centro symmetrical crystal structure. Piezo-phototronic effect can be applied to regulate the charge carriers’ generation, separation, transport, and recombination by controlling the Schottky barrier height of Metal semiconductor contact or built-in potential of p-n junction. Recent studies have shown that Group IV Monochalcogenides have a higher piezoelectric constant in comparison with those predicted values in other two-dimensional (2D) materials. This work aims to investigate theoretically the material properties for piezo-phototronics. The performance of 2D piezo-phototronic solar cells has been studied using by monolayer group IV monochalcogenides: SnSe, SnS, GeSe, and GeS metal–semiconductor contact. The modulation ratio by piezoelectric charges has been investigated under applied external strains. The piezo-phototronic effect plays a key role on the enhancement of the performance in solar cell. This study opens a new window to produce high-efficiency solar cell based on the promising group IV monochalcogenides.