Commitment and Contingencies - Narrative (Details) - USD ($) $ in Thousands	3 Months Ended			9 Months Ended
	Dec. 31, 2021	Mar. 31, 2021	Dec. 31, 2020	Dec. 31, 2021	Dec. 31, 2020	Sep. 30, 2021
Commitments and Contingencies Disclosure [Abstract]
Commitment to acquire equipment and services	$ 7,400			$ 7,400
Cumulative purchases made to date	7,200			7,200
Reimbursement received from government agency	119			347
Amount purchased		$ 270
Remaining accounts payable to vendors	135	$ 124		135
Contract for epiwafer technology						$ 900
Option in addition to contract for epiwafer technology						$ 500
Payments Received On Government Contracts	2			5
Rent expense	196		$ 237	661	$ 659
Rental income from noncancelable sublease	0		$ 45	0	$ 136
Future minimum rental payments to be received under sublease	$ 0			$ 0