▁levels ▁different ▁from ▁ ▁those ▁of ▁the ▁bulk . ▁This ▁difference ▁occurs ▁because ▁these ▁states ▁cannot ▁be ▁described ▁with ▁periodic ▁Blo ch ▁waves ▁due ▁to ▁the ▁change ▁in ▁electron ▁potential ▁energy ▁caused ▁by ▁the ▁missing ▁ion ▁cores ▁just ▁outside ▁the ▁surface . ▁Hence , ▁these ▁are ▁local ized ▁states ▁that ▁require ▁separate ▁solutions ▁to ▁the ▁Sch r öd inger ▁equation ▁so ▁that ▁electron ▁energ ies ▁can ▁be ▁properly ▁described . ▁The ▁break ▁in ▁period icity ▁results ▁in ▁a ▁decrease ▁in ▁conduct ivity ▁due ▁to ▁defect ▁scatter ing . ▁ ▁Electron ic ▁Energy ▁Level s ▁of ▁Sem icon duct or ▁D ang ling ▁B onds ▁ ▁A ▁simpler ▁and ▁more ▁qual itative ▁way ▁of ▁determ ining ▁d ang ling ▁bond ▁energy ▁levels ▁is ▁with ▁Harrison ▁diag rams . ▁Met als ▁have ▁non - direction al ▁bond ing ▁and ▁a ▁small ▁Deb ye ▁length ▁which , ▁due ▁to ▁their ▁charged ▁nature , ▁makes ▁d ang ling ▁b onds ▁incon sequ ential ▁if ▁they ▁can ▁even ▁be ▁considered ▁to ▁exist . ▁Sem icon duct ors ▁are ▁die lect rics ▁so ▁electrons ▁can ▁feel ▁and ▁become ▁tra pped ▁at ▁defect ▁energy ▁states . ▁The ▁energy ▁levels ▁of ▁these ▁states ▁are ▁determined ▁by ▁the ▁atoms ▁that ▁make ▁up ▁the ▁solid . ▁Figure ▁ 1 ▁shows ▁the ▁Har isson ▁diagram ▁for ▁the ▁element al ▁sem icon duct or ▁Si . ▁From ▁left ▁to ▁right , ▁s - orb ital ▁and ▁p - orb ital ▁hy brid ization ▁prom otes ▁sp 3 ▁bond ing ▁which , ▁when ▁multiple ▁sp 3