dd command*1 in UNIX reads and writes data in specified bytes or blocks at specified devices. It is used to backup of HDD or USB memory at partition or sector level, or convert from an optic medium to ISO file.
Although Windows doesn't have similar command, DD for Windows*2 is one option as its alternative.
Generating binary file
"Set-Content" is cmdlet basically for handling string. It can replace string in specified files. If specified file doesn't exist, it make new file including specified string.
Specifying byte array instead of string, user can make a binary file. Example, next code outputs "my_binary.dat" as 128KB binary file.
Open this file with binary editor, it is found that this code did the same thing as "/dev/zero".