create a circular button in flutter code example

Example: circular button in flutter

Container(
                      width: 90,
                      height: 90,
                      child: RaisedButton(onPressed: (){
                      },
                        color: Colors.deepOrange,  
                        textColor: Colors.white,
                        shape: CircleBorder(side: BorderSide.none),
                        child: Text('Login',style: TextStyle(
                            fontSize: 20.0
                        ),
                        ),
                      ),
                    )