DESIGNING HIGH-PERFORMANCE PHOTOTRANSISTORS USING SEMICONDUCTOR NANOMATERIALS

Abstract

Background: Phototransistors are vital in optoelectronics for their high sensitivity and broad spectral response, yet improving key metrics like responsivity, detectivity, and response time remains challenging. Semiconductor nanomaterials—with tunable band gaps, high carrier mobility, and strong light interaction—offer promising solutions.

Objective: This study designs and fabricates high-performance phototransistors using GaN-ZnO solid solution nanowires and WS₂–InGaZnO heterojunctions, investigating how band gap engineering, synthesis conditions, plasmonic enhancement, and heterostructure formation affect device performance.

Methods: GaN-ZnO nanowires with varying ZnO content were synthesized and deposited on Si/SiO₂ substrates, forming phototransistor channels. Performance was evaluated across synthesis temperatures and durations. Ag nanoparticles were added for plasmonic enhancement. WS₂–InGaZnO heterojunctions were fabricated using CVD and sputtering. Devices employed bottom-gate architectures with Ti/Au electrodes. Key parameters—photocurrent, responsivity, detectivity, response time, and stability—were measured.

Results: Band gap tuning from 3.4 eV (GaN) to 2.6 eV (Zn-rich) improved visible light absorption. Optimal synthesis at 850°C achieved responsivity of 95.3 A/W and detectivity of 2.1 × 10¹¹ Jones. Ag nanoparticle decoration enhanced responsivity to 131.7 A/W and reduced response time to 5.9 ms. WS₂–InGaZnO heterojunctions showed superior performance with 122.5 A/W responsivity, 3.8 × 10¹¹ Jones detectivity, and 91.7% stability over 50 cycles.

Conclusion: Band gap-engineered nanowires, plasmonic enhancement, and heterojunction integration significantly improve phototransistor performance, paving the way for next-generation broadband, high-sensitivity photodetectors for optoelectronic applications.