Reportable Segments - Schedule of Reportable Segment Information (Details) - USD ($) $ in Thousands		3 Months Ended		6 Months Ended
		Mar. 31, 2024	Mar. 31, 2023	Mar. 31, 2024	Mar. 31, 2023	Sep. 30, 2023
Segment Reporting Information [Line Items]
Net Revenues		$ 25,433	$ 33,310	$ 50,353	$ 54,868
Operating income (loss)		1,363	519	(7,571)	(2,161)
Identifiable Assets		116,474		116,474		$ 137,021
Operating Segments | Semiconductor
Segment Reporting Information [Line Items]
Net Revenues		17,441	22,047	34,968	38,934
Operating income (loss)		896	2,950	1,977	3,819
Identifiable Assets		63,986		63,986		72,466
Operating Segments | Material and Substrate
Segment Reporting Information [Line Items]
Net Revenues		7,992	11,263	15,385	15,934
Operating income (loss)		900	297	(6,943)	930
Identifiable Assets		50,579		50,579		61,576
Non-Segment Related
Segment Reporting Information [Line Items]
Operating income (loss)		(433)	$ (2,728)	(2,605)	$ (6,910)
Identifiable Assets	[1]	$ 1,909		$ 1,909		$ 2,979

[1] * Non-segment related assets include cash, property, and other assets.