Business Segment Information - Schedule of Business Segment Information (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Mar. 31, 2021	Mar. 31, 2020	Sep. 30, 2020
Segment Reporting Information [Line Items]
Net revenues	$ 19,790	$ 14,460	$ 37,765	$ 35,152
Operating income (loss)	171	(972)	1,225	665
Identifiable assets	107,936		107,936		$ 102,098
Operating Segments | Semiconductor
Segment Reporting Information [Line Items]
Net revenues	17,119	11,992	32,694	29,224
Operating income (loss)	1,665	(18)	3,862	2,704
Identifiable assets	56,079		56,079		51,648
Operating Segments | Material and Substrate
Segment Reporting Information [Line Items]
Net revenues	2,671	2,468	5,071	5,285
Operating income (loss)	(253)	421	(319)	955
Identifiable assets	19,714		19,714		12,717
Non-Segment Related
Segment Reporting Information [Line Items]
Net revenues				643
Operating income (loss)	(1,241)	$ (1,375)	(2,318)	$ (2,994)
Identifiable assets	$ 32,143		$ 32,143		$ 37,733