Thin film silicon materials and solar cells grown by pulsed PECVD technique

Abstract

The pulsed PECVD involves modulation of standard 13.56 MHz RF plasma in the kHz range. This allows an increase in the electron density during the 'ON' cycle, while in the 'OFF' cycle neutralizing the ions responsible for dust formation in the plasma. In this work, we report the development of state of the art nano-crystalline Si (nc-Si:H) materials using Pulsed PECVD technique with 220 crystallite orientation, grain size of ~200 Å, low O concentration and a minority carrier diffusion length, L d , of ~1.2 µm. The crucial effects of p/i interface and the incubation layer have been investigated and an efficiency of ~7.5% for single junction nc-Si:H p-in device has been achieved for the i-layer thickness of 1.4 µm, using non optimized textured substrates.

Electrical and structural properties of nano-crystalline silicon intrinsic layers for nano-crystalline silicon solar cells prepared by very high frequency plasma chemical vapor deposition

“…When the power is further increased to 40 and 50 W, the reflectance spectra do not show any peaks at 275 and 365 nm confirming that the films are amorphous as shown in Raman spectra Fig. 3(b) [25].…”

Pulsed PECVD for the Growth of Silicon Nanowires

“…PPECVD is known to increase the deposition rate of a-Si, ncSi and μc-Si while suppressing the dust formation that tends to occur when the deposition rate is increased simply by increasing the plasma power [9]. It has also been previously shown that the use of a silane plasma increases the growth rate of silicon nanowires [2].…”

“…Use of suitable apparatus allows the modification of the modulation frequency as well as the ratio of plasma on time to off time (mark space ratio). For the deposition of microcrystalline silicon thin films a modulation frequency of between 1kHz and 100kHz and a mark space ratio of 10% to 50% is used [8].This technique increases the deposition rate of a-Si, nc-Si and μc-Si while suppressing the dust formation that tends to occur when the deposition rate is increased simply by increasing the plasma power [9].…”

Flexible Solar Cells and Stable High-Efficiency Four-Terminal Solar Cells Using Thin-Film Silicon Technology

“…From a device point of view, the critical factors are the minimization of the incubation layer, control of interfaces, effect of textured substrate, etc. [12][13][14]. Of all the deposition techniques studied so far in the development of nc-Si:H devices, pulsed PECVD technique offers a promising approach, as described below.…”