deletions | additions       diff --git a/P_N_junction_components_Could__1.md b/P_N_junction_components_Could__1.md  index 4266524..0584470 100644  --- a/P_N_junction_components_Could__1.md  +++ b/P_N_junction_components_Could__1.md 
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Could other materials be used?  Why a heterojunction vs a homojunction?  Recombination radiation.