Keithley Series 2600 - Page 106

A-53
APPENDIX A
Scripts
Rev1: JAC 6.26.2007
]]--
------------------ Keithley TSP Function ------------------
function FET_Thres_Search(vdssource, lowvgs, highvgs, targetid) --Configure SMUA to source
a user-defined voltage on
--the drain-source (Vds) while SMUB sources a voltage on --the gate-source (Vgs). VGS is
varied using a binary
--search algorithm between a maximum and minimum Vgs value, and the drain-source current
(Id) is measured.
--If measured value is outside the tolerance, search is performed again until the value
falls within the
--specified range or the iteration limit is reached.
--Returns measured Vds, Vth, and Id.
local l_k --binary search loop count variable
local l_k_max = 20 --Maximum loop counts
local l_vds_source = vdssource --vdssource value
local l_high_vgs = highvgs --Start Ib high limit
local l_low_vgs = lowvgs --Start Ib lo limit
local l_target_id = targetid --Target Ic for binary search
local l_nplc = 1
local l_vgs_source = 0--Gate-sourced voltage
local l_id_meas --Drain-source measured voltage
--Default values and level check
if (l_vds_source == nil) then --Use default value
l_vds_source = 0.5
end --if
if (l_low_vgs == nil) then --Use default value
l_low_vgs = 0.5
end --if
if (l_high_vgs == nil) then --Use default value
l_high_vgs = 1.1
end --if
if (l_target_id == nil) then --Use default value
l_target_id = 1e-6
end --if
smua.reset() --Reset SMU
smub.reset() --Reset SMU