There is a way to get their tech. You have to take it. By force. Its not easy and the best method is to piss them off and get their fleets to attack you're most powerful defenses. Either that or use a systemcraft or herculean by which point you'll be past the need for phanon tech. You can take their planets to get the tech and I think its a decision to attack the vault once you have the planet. It's very difficult though and you need the ACOT armies to do it. I believe the phanon tier is a bit better than alpha but I may be wrong.