Flutter :- Create circular border around icons

I am doing some mistakes in my above code. but I have figured out and here is the new code.

Container(
                  margin: EdgeInsets.all(20),
                  padding: EdgeInsets.all(10),
                  decoration: BoxDecoration(
                      borderRadius: BorderRadius.circular(100),
                      border: Border.all(width: 2, color: Colors.white)),
                  child: Icon(
                    Icons.cancel,
                    color: Colors.white,
                  ),
                )),

Also if you want to make complete Widget clickable then you can use it like this.

GestureDetector(
            onTap: () {
              //Navigator.of(context).pop();

            },
            child: new Align(
                alignment: Alignment.bottomRight,
                child: Container(
                  margin: EdgeInsets.all(20),
                  padding: EdgeInsets.all(10),
                  decoration: BoxDecoration(
                      borderRadius: BorderRadius.circular(100),
                      border: Border.all(width: 2, color: Colors.white)),
                  child: Icon(
                    Icons.cancel,
                    color: Colors.white,
                  ),
                )),
          ),

Container(
            decoration: BoxDecoration(
              shape: BoxShape.circle,
              border: Border.all(color: Colors.white)
            ),
            child: Icon(Icons.check, color: Colors.white,),
          )

or you can use Material if you're going to need some fancy effects:

Material(
            color: Colors.transparent,
            shape: CircleBorder(
              side: BorderSide(color: Colors.white)
            ),
            child: Icon(Icons.check, color: Colors.white,),
          )