Full text loading...
(a) Schematic of CNT test structure with GST thin film sputtered on top. (b) Measured current-voltage of a typical CNT ( , ) before and after GST deposition. The inset displays the measured current vs back-gate voltage, indicating metallic behavior.
Measured and imaged phase change of GST covering CNT heater. (a) Consecutive current sweeps to progressively higher current. Each state is preserved when the GST is returned to zero current (room temperature). (b) Topographic AFM before any current is applied and [(c)–(e)] after current sweep to , 130, and , respectively. The latter correspond to traces no. 3, 6, and 7 labeled in (a). As current passes through the device, the CNT heats up and crystallizes the surrounding GST. In (c), the color profile shows the qualitative Joule heating temperature rise of the CNT, e.g., see Refs. 8 and 9 . The GST near the middle of the CNT is crystallized first, illustrating the role of heat sinking at the CNT contacts (thermal healing length ). At higher currents the GST covering the entire CNT is crystallized as shown in (d), and eventually fails (e).
Simulation of GST heating and phase change with CNT heater. (a) Device structure used in the 3D simulation mimics the experimental test structures. (b) Measured (symbols) and simulated (lines) characteristics of a typical metallic CNT covered by GST. The FE model predicts a sudden increase in overall conductivity as the GST changes to hcp crystalline state. [(c) and (d)] Cross-sectional temperature (top) and conductivity (bottom) of GST at the middle of the CNT at and , respectively. The simulations suggest that noticeable voltage snapback only occurs when of GST near the CNT transitions to hcp phase.
Article metrics loading...