Record performance in intrinsic, impurity-free lateral diamond photoconductive semiconductor switches
Zhuoran Han, J. Lee, Anik Mazumder, Hubert N. Elly, Stephen Messing, Andrey E. Mironov, C. Bayram
Abstract
Photoconductive semiconductor switches (PCSSs) are fabricated on type IIa diamond substrates with varying boron and nitrogen impurity levels (<1014–1016 cm−3). The photoresponse of lateral PCSS is reported over the incident laser wavelength range (212–240 nm), energy per pulse (5–65 μJ), and DC bias (−1.2 to +1.2 kV). The PCSS device with the lowest boron and nitrogen impurity concentration achieves the highest normalized responsivity of 9.1 × 10−8 A-cm/W-V, peak photocurrent of 8.0 A, and on/off ratio of 2.3 × 1011 at a DC bias of +1.2 kV with the potential for even higher currents at increased DC bias. All PCSS display fast rise times (<3 ns), limited by the laser's rise time. However, photoresponse measurements reveal that higher impurity levels reduce the photocurrent and decrease the on/off ratio. These results highlight the performance advantages of using low background concentration type IIa diamond substrates for PCSS fabrication and present a promising route toward advanced high-power, high-speed diamond-based switches.