The present invention is directed to a spare tire cart suitable for mounting to the undercarriage of a vehicle. The semiconductor layer and the forming method thereof according to the present invention includes a first SiGe film or SiGeC film containing Ge of which the concentration become equal to a thermal expansion coefficient of silicon oxide and a second SiGe film or SiGeC film formed on the first film. One or more features are formed in the first semi-rigid barrier sheet accommodating components housed between the interior and exterior panels. In response, the data manager retrieves the appropriate information from the travel data stored in the travel data storage unit and transmits this information to the user.