There is a square with rounded corners. At the bottom on the inside of the square about a quarter-of-the-way from the corner, a line goes up almost to the top, then it comes down to the right at a 45 degree angle for a length equal to half of a side of the square.
This is a NFC C icon. It is available in PNG and vector. Downloading is free for PNGs up to 100x100px.