What are the Data types used in excel EXCEL..?

Yes, string fields in Excel are treated as Unicode string fields by the driver. Here is some content written about moving data in the other direction that applies here too:

Data types. The Excel driver uses only six data types, which Integration Services maps as follows:

• Numeric – double-precision float (DT_R8)
• Currency – currency (DT_CY)
• Boolean – Boolean (DT_BOOL)
• Date/time – date (DT_DATE)
• String – Unicode string, length 255 (DT_WSTR)
• Memo – Unicode text stream (DT_NTEXT)