【Powershell】日付を2020-03-03T17:00:00の形式に変換

PS C:\> $DATE="2020/2/12"
PS C:\> $TIME="9:00"
PS C:\> [datetime]$DATETIME=($DATE + " " + $TIME)
PS C:\> Get-Date $DATETIME -Format s
2020-02-12T09:00:00
PS C:\>