Further information about modified structure APD Akiko Hirayama

Further information about modified structure APD Akiko Hirayama (talk by KM) (Nara Women’s University, Japan) B 2 GM ECL session 2012 Jul. 23 rd 1

Device structure Modified APD • To improve Q. E. for short (~310 nm) l. • Two 1× 1 cm 2 and three 5× 5 mm 2 in Nara. • As reported in June 29 th ECL meeting, – 1× 1 cm 2 No. 1 and 5× 5 mm 2 No. 2 are found to tend to have noise pulse after keeping bias ON for a couple of days. – More information have been gotten for 5× 5 mm 2 No. 2.

By keeping HV ON, gradually change? Noise pulse appear at 410 V 420 HV to cause noise pulse 410 2 days later, noise pulse appear at 392 V 電圧[V] 400 390 380 Went down to 372 V 370 360 Finally it appears at nominal HV. M=50 at 372 V 350 340 0 20 40 60 80 時間[hour] 100 120 140

I-V curve (5 mm. X 5 mm No 2) 0, 0001 1 E-05 Since v-axis is log scale, generally looks similar to the HPK spec. sheet. , but… 1 E-06 電流[A] 1 E-07 1 E-08 1 E-09 1 E-10 1 E-11 1 E-12 1 E-13 0 100 200 300 電圧[V] 400 500

Further test by keeping at 372 V 電流[n. A] Once HV OFF, then apply 372 V(M=50) a couple of days later, then kept ON for two days. 1, 8 Leakage current 1, 6 1, 4 1, 2 1 0, 8 0, 6 0, 4 0, 2 0 0 10 change (5 mm. X 5 mm No 2) On the spec. sheet by HPK, it was 1. 0 n. A. 20 30 時間[hour} 40 50 Note: just after HV ON again, it looks quiet.

Currently on-going • After these measurements, 5× 5 mm 2 No. 2, noise pulse height and rates are – 5~10 m. V, ~500 Hz(Vth=5 m. V) at 380 V – 10~20 m. V, 10~30 k. Hz(Vth=5 m. V) at 390 V. – Note that cataloged ones are much more robust, operational at even M=50 voltage+30 V. • More quiet pieces being measured to compare. • Feedback to HPK is being made. – Their tests (I-V, Gain-V, Cdet-V) before shipping is done in several minutes. – Our available information is sorted up. 6