High-Temperature Microwave Performance of Submicron AlGaN/GaN HEMTs on SiC

Abstract

<para xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> The effect of temperature on the small-signal radio-frequency (RF) performance of submicron AlGaN/GaN high-electron-mobility transistors on SiC has been studied from room temperature (RT) up to 600 K. A relation between ambient and channel temperatures has been established by means of finite-element simulations. The thermal behavior of the intrinsic parameters <formula formulatype="inline"><tex Notation="TeX">$C_{\rm gs}$</tex></formula>, <formula formulatype="inline"><tex Notation="TeX">$C_{\rm gd}$</tex></formula>, <formula formulatype="inline"><tex Notation="TeX">$g_{m, {\rm int}}$</tex></formula>, and <formula formulatype="inline"><tex Notation="TeX">$g_{\rm ds}$</tex></formula> has been extracted accurately from RF measurements by means of the small-signal equivalent circuit. Main dc parameters <formula formulatype="inline"><tex Notation="TeX">$(I_{D}, g_{m, {\rm ext}})$</tex></formula> show reductions close to 50% between RT and 600 K, mainly due to the decrease in the electron mobility and drift velocity. In the same range, <formula formulatype="inline"><tex Notation="TeX">$f_{T}$</tex></formula> and <formula formulatype="inline"><tex Notation="TeX">$f_{\max}$</tex> </formula> suffer a 60% decrease due to the reduction in <formula formulatype="inline"><tex Notation="TeX">$g_{m, {\rm ext}}$</tex> </formula> and a slight increase of <formula formulatype="inline"><tex Notation="TeX">$C_{\rm gs}$</tex></formula> and <formula formulatype="inline"><tex Notation="TeX">$C_{\rm gd}$</tex></formula>. An anomalous thermal evolution of <formula formulatype="inline"><tex Notation="TeX">$C_{\rm gd}$</tex></formula> at low <formula formulatype="inline"><tex Notation="TeX">$I_{D}$ </tex></formula> has been identified, which is indicative of the presence of traps. </para>