Rijndael in PHP - php

Question

I am trying to encrypt a string with a key and iv with Rijndael in PHP.
I have wrote this in VB .Net and the result is the expected one:
'This is the byte Array of "1234567890ABCDEF1234567890ABCDEF". I am using this for IV
Private _key1 As Byte() = New Byte(15) {CByte(18), CByte(52), CByte(86), CByte(120), CByte(144), CByte(171), _
CByte(205), CByte(239), CByte(18), CByte(52), CByte(86), CByte(120), _
CByte(144), CByte(171), CByte(205), CByte(239)}
Public Sub Init()
Dim sKey As String = "D6850B89370BD603BD48CEAD43488639DE3ABE73D2CF7C54B0CF72D2FB06E162"
Dim resBytes As Byte() = Me.EncryData("a", sKey)
File.WriteAllBytes("C:/myFile.txt", resBytes)
End Sub
Public Function EncryData(sPath As String, sKey As String) As Byte()
Return Me.AESEncrypt(plainText, Me.Data_Hex_Asc(sKey))
End Function
Public Function Data_Hex_Asc(ByRef Data As String) As Byte()
Dim str1 As String = ""
Dim list As New List(Of Byte)()
While Data.Length > 0
Dim num As Integer = CInt(Convert.ToChar(Convert.ToUInt32(Data.Substring(0, 2), 16)))
Dim str2 As String = Convert.ToChar(Convert.ToUInt32(Data.Substring(0, 2), 16)).ToString()
list.Add(CByte(Convert.ToUInt32(Data.Substring(0, 2), 16)))
str1 += str2
Data = Data.Substring(2, Data.Length - 2)
End While
Return list.ToArray()
End Function
Public Function AESEncrypt(plainText As String, aByte As Byte()) As Byte()
Dim symmetricAlgorithm As SymmetricAlgorithm = DirectCast(Rijndael.Create(), SymmetricAlgorithm)
Dim bytes As Byte() = Encoding.UTF8.GetBytes(plainText)
symmetricAlgorithm.Key = aByte
symmetricAlgorithm.IV = Me._key1
Dim memoryStream As New MemoryStream()
Dim cryptoStream As New CryptoStream(DirectCast(memoryStream, Stream), symmetricAlgorithm.CreateEncryptor(), CryptoStreamMode.Write)
cryptoStream.Write(bytes, 0, bytes.Length)
cryptoStream.FlushFinalBlock()
Dim numArray As Byte() = memoryStream.ToArray()
cryptoStream.Close()
memoryStream.Close()
Return numArray
End Function
Now the PHP version of that:
$AES_KEY = "D6850B89370BD603BD48CEAD43488639DE3ABE73D2CF7C54B0CF72D2FB06E162";
$key = pack('H*', $AES_KEY);
$plaintext = "a"; ;
$iv = pack('H*', "1234567890ABCDEF1234567890ABCDEF");
$enc_text = mcrypt_decrypt(MCRYPT_RIJNDAEL_128, $key, $plaintext, MCRYPT_MODE_CBC, $iv);
The result from PHP code is different from the VB's.
Any suggestions for different php approach?
VB .net implementation of Rijndael uses as default padding: PKCS7 and mode: CBC
Results: vb .net: PFΑ&\O?„\LϋAμCt php:_yJ_½%sAj«SUhA
16 chars length, both of them.