I looked into Stanford's LDT PhD and MIT's Lifelong Kindergarten, but I've applied to Language and Literacy programs at schools that excel at educational technology research, digital centres, labs, etc. I live in Canada, and though I'm from the U.S., I can't imagine going back for an extended period of time right now. Also, tuition for Canadian Education PhDs is less than $6000 a year and most programs are fully funded to $30k with additional funding opportunities.
Message me if you want to ask questions about MET.