Summary of Simulations from KIT Robert Eber, Martin Printz

Contents Simulation all carried out with Synopsys Sentaurus Layout Performance – Un-irradiated charge collection

Electric Fields – n-bulk before irradiation Comparing (p90,w20), (p240,w20), (p240,w60), (p90,w60) Highest fields for very small width/pitch (p90,w60) not converging (too high fields)

P-stop Simulation P-type sensors require strip isolation – best configuration? Sensor – Implant 20µm, pitch 90µm – w/p = 0.22 P-stop implant max conc. 5x10 16 cm -2 Atoll Simulated Atoll version P-stop width varying between 4µm and 8µm P-stop distance between near-strip and half-pitch Distance = 0Distance = 1 P-stop width

Electric Field with p-stop High fields with low distance to strip (breakdown) p-stop at large distance to strip and small width ensure good HV operation E (V/cm) Potential (V) S tr ip

Effects of p-stop on Eta Distribution P-stop affects electric field and therefore charge sharing between strips – Effect on eta (charge sharing between strips) Eta also depends on oxide charge (irrad. Sensors) More charge sharing with higher irrad. (only oxide charge simulated here) CBC: lower charge sharing good for binary readout

Electric Field p-spray Cut 100nm below oxide P-spray conc = 4e15cm-3 Qox=1e11c m-2 200µm Implant Depth

Irradiated Strip Sensors Effective Irradiation Model (tuned especially for protons) ParameterDonorAcceptor EnergyE V eVE C eV Concentration (cm 3 )5.598 * F – 0.959e * F e14 σ(e)1.0e-14cm 2 σ(h)1.0e-14cm 2

Electric Field at the Strips – n-bulk F=1e15neq/cm2 Low Qox High Qox Increase in E worse with irradiation

Electric Field at the Strips – n-bulk F=3e14neq/cm2 Soft breakdown due to very high electric fields at the strips with higher oxide charge

P-BULK

Electric Fields – p-bulk Sensors Comparison between 320µm and 200µm thick FZ p-bulk sensors Not much higher electric fields than for 320µm devices at strips (center of strip) Higher fields in the bulk Lower fields for higher oxide charge – intrinsically good! Higher Qox

Electric Fields at the Strips – FZ320P At low oxide charge: Electric fields increase with fluence Not critical Strip Alu overhang P-stop

Electric Fields at the Strips – FZ320P At high oxide charge, electric fields even lower… (tbc) Strip Alu overhang P-stop

Electric Fields at the Strips – FZ200P 200µm thick sensors Influence of p-stop doping after irradiation: higher fields at higher doping Strip Alu overhang P-stop

Electric Fields at the Strips – FZ200P High p-stop doping and high oxide charge: very high electric fields at p-stop Strip Alu overhang

Summary of design (electric fields) Before irradiation – Larger pitch/width reduces electric fields between the strips – P-stop should be placed away from the strips – Small p-stop width for lower electric fields at p-stop After irradiation – N-bulk sensors perform worse with higher oxide charge – Electric fields in p-bulk sensors lower with higher oxide charge at the strips – 200µm thick sensors show same behaviour as 320µm – High p-stop doping may be worse after irradiation?

PERFORMANCE

Charge Collection Efficiency

Charge Loss between Strips