In formal English "woken" is not correct. You would say "I have just awakened". Modern usage is less formal, though, and "woken" is accepted. So both "I have just woken up" and "I just woke up" are fine (note: "I have just woken", not "I just have woken").

The grammatically correct form is “I have just woken up”. However, the colloquial version “I just woke up” is accepted. “I just have woken up” is incorrect. Regards!

I know that this topic has been beaten to death (idiom that means talked over too many times), but there was a general question behind what you asked that I would like to answer. Most of the time the subject of the sentence (I, you, he/she/it, etc.) is not separated from the verb (the action). Which is why "I have just..." is okay but "I just have..." won't work.

'Have woken' is the present perfect tense, and 'woke' is the past simple. In British English we use the present perfect tense when we use 'just' to talk about the past. In American English it's common to use the past simple with 'just'. So 'I just woke up' would probably sound fine to an American English speaker, but sounds a little odd to someone from the UK. We still understand what you mean though. Go with the one that matches the nationality if your teacher!

It's just overly past tense. In the states we just keep real simple and to the point