Activation of silicon implanted with phosphorus and boron atoms by microwave annealing with carbon powder as a heat source

Abstract

We report the activation of silicon implanted with phosphorus and boron atoms by microwave annealing using carbon powder as a heat source. Silicon substrates were covered with carbon powder and then irradiated with 2.45 GHz microwaves using a commercial microwave oven. Carbon powder effectively absorbs microwaves and heats itself at 1000°C. Silicon substrates are heated by thermal conduction. We carried out implantations of phosphorus atoms at a concentration of 1.0 ' 10 15 cm %2 at 75 keV and boron atoms at a concentration of 1.0 ' 10 15 cm %2 at 25 keV for p-and n-type silicon substrates, respectively. Microwave annealing at 1000 W for 120 s achieved sheet resistivities of 140 and 85 Ω/sq for the phosphorus-and boron-implanted samples, respectively. It also realized the recrystallization of surface amorphized regions caused by implantation. Moreover, low surface recombination velocities of 3.8 ' 10 2 and 2.7 ' 10 2 cm/s were obtained at the top implanted surfaces for the phosphorus-and boron-implanted samples, respectively. Typical diode rectified characteristics and solar cell characteristics with a conversion efficiency of 10.1% were successfully obtained.

Indium gallium zinc oxide layer used to decrease optical reflection loss at intermediate adhesive region for fabricating mechanical stacked multijunction solar cells

“…Heating at 350 °C for 1 h increased the resistivity of the IGZO layer from 0.0011 to 0.056 Ω cm, whose connecting resistivity was 1.1 × 10 −6 Ω cm 2 , which is much lower than 1.0 Ω cm 2 . [34][35][36][37][38][39][40] On the other hand, the IGZO film with 0.056 Ω cm only causes a very small free carrier absorption with an absorption coefficient of 0.2 cm −1 and an extinction coefficient of 2.7 × 10 −6 at the longest λ 2 of 1600 nm, as shown in Table I, which is in accordance with the free carrier absorption theory. 34,[41][42][43] IGZO layers are therefore optically transparent and electrically conductive.…”

Photoinduced carrier annihilation in silicon pn junction

“…Most of boron and phosphorus atoms were located within 60 nm from the silicon surfaces. The implanted samples with the SiO 2 layers coated on the surfaces were subsequently heated by microwave irradiation using a commercial 2.45 GHz microwave oven at 1000 W for a duration of 150 s. 21) The samples were completely covered with carbon powders 2-µm-diameter for effective heating and placed on a quartz glass substrate with low heat conductivity to keep the heat energy in the sample region. The SiO 2 layers prevented the incorporation of other materials such as carbon into silicon.…”

Understanding the microwave annealing of silicon

“…[5][6][7]22 Other measures, such as using a metal film covering, can assist silicon wafer heating. 27 The metal covering can be heated significantly as a result of strong absorption of microwave energy via ohmic conduction loss in the material.…”