4. BALANCE SHEET DETAIL - Prepaid expenses and other current assets (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Mar. 31, 2019
Prepaid expenses and other current assets:
Prepaid tooling and masks	$ 802	$ 535
Prepaid income taxes	54	39
Escrow deposit	1,000	1,000
Other receivables	379	321
Other prepaid expenses and other current assets	1,000	605
Total prepaid expenses and other current assets	$ 3,235	$ 2,500