Current‐Induced Joule Heating and Electrical Field Effects in Low Temperature Measurements on TIPS Pentacene Thin Film Transistors.

The channel temperature (T_ch) of solution‐processed 6,13‐bis(triisopropylsilylethynyl)‐pentacene (TIPS pentacene) thin film transistors (TFTs) is closely monitored in real time during current–voltage (I–V) measurements carried out in a He exchange gas cryostat at various base temperatures (T_b) between 300 K and 20 K. This is done using a platinum (Pt) resistance temperature sensor embedded within the transistor channel. Under large gate (V_g) and source‐drain (V_ds) voltage biases, an increase in T_ch is observed, the magnitude of which depends on the thermal conductivity of the substrate. The increase in T_ch is associated with a simultaneous increase in the transistor drain current (I_d) and becomes particularly pronounced at cryogenic T_b. These experimental observations are rationalized using a 1D theoretical model and are attributed to current‐induced Joule heating. However, even though the heating of the channel unquestionably plays an important role, the corresponding amount of increase in I_d at cryogenic T_b and large voltage biases cannot be fully accounted for unless at low temperatures μ_TIPS is enhanced in the presence of strong electrical fields. Therefore it is concluded that the I–V characteristics of TIPS pentacene TFTs at low T_b and large voltage biases are a result of a complex interplay between current‐induced Joule heating and electrical field effects. [ABSTRACT FROM AUTHOR]