I recommend using the tree /f command if you just wanted to see what dir /s/b did for you while in a powershell console:

C:\test>tree /f
C:.
├───a
├───anotherdir
│       somefile.txt
│       somefile2.txt
│       somefile3.txt
│
└───anotherdir2

If you are writing a script or something I like the answer @Bob gave:

(dir -r).FullName