Development and evaluation of germanium telluride phase change material based ohmic switches for RF applications

Abstract

We report on the device structure and performance of germanium telluride phase change material based ohmic RF switches. Two main types of the phase change switches using direct and indirect heating methods have been designed, fabricated and measured to analyze and compare the performance of germanium telluride in RF switch applications. Both types of switches are proven to have an insertion loss of less than 0.6 dB and an isolation of more than 13 dB for up to 20 GHz. Good linearity and power handling capability results are also measured. A reconfigurable bandpass filter using the indirectly heated phase change switch has also been developed, and shows promising performance. Efforts have been made to further analyze the issues with switching reliability, and explore possible ways of improving the performance of phase change RF switches.

Memristive Systems Based on Two-Dimensional Materials

“…Modern switches are implemented using transistor or microelectromechanical devices, both of which are volatile, and the latter also requires a large switching voltage that is not suitable for mobile technologies. Recently, phase change switches have attracted interest [29], but the until the next cycle [23].…”

“…The extracted resistance when the state is On, R ON ≈ 11 ohms and capacitance when the state is Off, C OFF ≈ 7.7 fF. This results in a cut-off frequency, which is used to estimate the RF switches (a figure of merit (FOM)) [29,30] f co = 1/(2πR ON C OFF ) ≈ 1.8 THz. Further improvements, especially in terms of scaling, are expected to lead to a significant increase in FOM.…”

“…Further improvements, especially in terms of scaling, are expected to lead to a significant increase in FOM. A unique combination of independent LRS resistance and area-dependent HRS capacity gives a FOM that can be scaled to 100 s of THz by reducing the area of the device that determines advantages over phase-change switches [29,30], where the capacitance is proportional to the width, but R ON is inversely dependent, hence, prevents frequency scaling without significant compromise losses. In addition, the high stress of mechanical rupture and the easy integration of 2D materials onto soft substrates enable the production of flexible nonvolatile digital and analog/RF switches capable of withstanding mechanical cycling (Figure 22(e)).…”

Performance Comparison of Phase Change Materials and Metal-Insulator Transition Materials for Direct Current and Radio Frequency Switching Applications

“…These attributes make these devices promising candidates for future RF circuitry and also satellite applications. In addition, devices that are based on these innovative materials offer complementary metal oxide-semiconductor (CMOS) compatibility and simplified, low cost fabrication processes [3][4][5]. However, the power handling capability of VO 2 -based devices are relatively low compared to RF MEMS devices.…”

A Phase Change Material for Reconfigurable Circuit Applications

“…All these superior properties make GeTe a leading candidate for memory, as well as RF switching applications [9]. The main advantages of GeTe RF switches over the conventional microelectromechanical systems (MEMS) electrostatic switches (of the same size) are, including but not limited to the simpler fabrication method, long lifetime, large cut-off frequency (in THz), near zero in-state power consumption/lower switching voltages, high power handling capabilities, immune to radiation exposure (good for space applications), and the elimination of special packaging requirements [9][10][11][12][13]. Furthermore, the simpler design allows the integration of GeTe switches with various MEMS and CMOS devices.…”