  Funtionalized pentacene, 6,13-bis(triisopropylsilylethynyl)pentacene
(TIPS-pentacene), field-effect transistors(FET's) were made by thermal
evaporation or solution deposition method and the mobility was measured as a
function of temperature and light power. The field-effect mobility ($\mu$$_{\rm
FET}$) has a gate-voltage dependent activation energy. A non-monotonic
temperature dependence was observed at high gate voltage (V$_G$ $<$ -30 V) with
activation energy E$_a$ $\sim$ 60 - 170 meV,depending on the fabrication
procedure. The gate-voltage dependent mobility and non-monotonic temperature
dependence indicates that shallow traps play important role in the transport of
TIPS-pentacene films. The current in the saturation regime as well as mobility
increase upon light illumination and is proportional to the light intensity,
mainly due to the photoconductive response. Transistors with submicron channel
length showed unsaturating current-voltage characteristics due to the short
channel effect. Realization of simple circuits such as NOT(inverter), NOR, and
NAND logic gates are demonstrated for thin film TIPS-pentacene transistors.
