Design and simulation of InGaAs-based planar electronic nanodevices as terahertz rectifiers based on curvature coefficient analysis

The “Terahertz gap” frequencies between 0.1 to 10 THz possess unique characteristics with a lot of promising application in various fields such as safe imaging, medical and explosive detections. However, limited numbers of optimal (current responsivity, β > 3.5 V-1) detectors and sources in this region leave researchers only a few alternatives in exploring the region. In this work, characterizations using ATLAS device simulator aimed to increase β performance of Self-switching Diode (SSD) and simulations of new planar devices; the Planar Barrier Diode (PBD) and Self-switching Planar Barrier Diode (SSPBD) are reported. The β is mainly contributed by a parameter known as the curvature coefficient, γ which is derived from the current-voltage (I-V) behavior of the device. As such, the γ was analyzed in this work, not only by varying the device’s geometrical structure, but also by implementing different dielectric relative permittivity of the insulating material ranging from 1.0 – 10 under temperature range of 300 – 600 K. The results showed that increased temperature degraded the SSD’s and PBD’s rectifying performance due to increased reverse current which can deteriorate the nonlinearity of the device’s I-V characteristic. For SSD, the γ of ~32 V-1 and 30 V-1 has been achieved at 30 mV and zero-bias, respectively. The cut-off frequency, fc of SSD attained in this work was ~80 GHz, operating at unbiased condition. In addition, an enhanced barrier is introduced in the new PBD device, which contributed to higher switching speed in the channel. The working principle of the new PBD is explained using thermionic emission theory. By employing the optimized structure parameters, the zero-bias γ of ~4 V-1, with peak of ~14 V-1 at 0.10 V bias were achieved. With DC bias of 50 mV to exploit the rectification peak, the fc of the PBD was attained at 270 GHz. In addition, hybrid structure of SSPBD shows improved performance in fc with detection of 360 GHz at zero-bias. Zero-bias γ of ~6 V-1, with peak of ~19 V-1 at 70 mV bias were observed in the SSPBD. The β of >3.5 V-1 in all simulated devices indicates optimal conversion ability as a rectifying device. The results obtained in this work proved the functionality of SSD as mm-wave rectifiers, and the new devices of PBD and SSPBD as THz rectifiers and may assist in future improvement of the devices.