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SUMMARY:European materials research society spring meeting
DTSTART;VALUE=DATE:20190527
DTSTAMP:20260427T224110Z
UID:16d29e126d34fafddf01b6280b992607ca4bedd01d3c321899fb9812
CATEGORIES:Conferences - Seminars
DESCRIPTION:Angela Fioretti\nThe European materials research society (E-MR
 S) spring meeting will hold from May 27 to 31 in Nice (France). Angela Fio
 retti will have a talk on "Low-temperature GaN on Si as a transparent\, ca
 rrier-selective contact for heterojunction solar cells".\nAbstract:\nCarri
 er-selective\, passivating contacts have allowed silicon heterojunction (S
 HJ) cells to reach record-breaking efficiencies >26% when using all-back-c
 ontacted designs. However\, classical SHJ cell efficiency has been limited
  to 25.1% due in part to parasitic absorption losses up to 3 mA/cm2 in the
  a-Si layers. Materials with greater transparency could reduce this curren
 t loss and increase efficiency while using a simpler design. Gallium nitri
 de (GaN)\, with a bandgap of 3.4 eV and an advantageous band alignment wi
 th crystalline silicon\, could be applied as a transparent electron-select
 ive layer. One obstacle to this application is that GaN is typically grown
  above 800°C\; too hot for the SHJ thermal budget. Here\, we report on PE
 CVD GaN layers grown at <300°C on silicon. The influence of gas ratio and
  substrate pretreatment on film crystallinity was investigated by Raman sp
 ectroscopy and X-ray diffraction. An over-pressure of nitrogen was require
 d to obtain the GaN phase\, and either pre-nitridation or oxidation of the
  silicon surface led to enhanced crystallinity compared to growth on bare 
 silicon. Full SHJ cells using GaN as electron-selective contact were made\
 , with promising open-circuit voltages >500 mV. Still\, low conductivity o
 f the as-yet undoped GaN layers induced series resistance (Rs) losses that
  limited fill factor and cell efficiency. To address this\, we will report
  ongoing efforts to reduce Rs in GaN-contacted cells via doping of the nit
 ride layer.\n\n 
LOCATION:
STATUS:CONFIRMED
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