SQL Server :: Month In Format MM?

I need to return a string in the format YYYYMM but I am not able to figure out how to get the month in the format MM (02 for Feb). This is what I did

Create FUNCTION [dbo].[GetMonth](@Today DateTime)
RETURNS
nvarchar AS
BEGIN
Declare @mth nvarchar;
Set @mth = cast(month(@Today) As nvarchar);
IF month(@Today) < 10
Begin
Set @mth = '0' + cast(month(@Today) As nvarchar)
End
Return @mth;
END

This is returning a 0. I don't know what is wrong in the IF block.