Reducing the dependence of threading dislocation density on doping for GaAsP/GaP on Si

We compare ~1.7 eV GaAsP top cells grown on GaP/Si templates with different GaAs
y
P
1-y
/GaP buffer layer doping, either unintentionally-doped (UID) or Si-doped (n-type). Unlike our previous work showing 2.7× higher threading dislocation density (TDD) with n-type doping [1], we observed almost no change in TDD between GaAsP top cells grown on UID-buffers or n-buffers with our improved n-GaP buffer design. Similar GaAsP top cell device performance was achieved on UID- and n-buffers with AM1.5G efficiencies of 16.82% and 16.35%, respectively, despite TDD approaching 1×10
⁷
cm
^-2
.