We have measured C-V characteristics and temperature dependence of J-V characteristics of undoped hydrogenated amorphous silicon (a-Si:H) heterojunctions formed on p-type crystalline silicon (p c-Si) substrates with different resistivities. It has been found that an abrupt heterojunction model is valid for a-Si:Hlp c-Si heterojunctions, and the electron affinity of a-Si:H has been estimated as 3.93 ± 0.07 e V from C-V characteristics. The forward current of all the junctions studied shows voltage and temperature dependence expressed as exp( -ilEafl kT) exp(A V), where ilEa! and A are constants independent of voltage and temperature, being successfully explained by a multitunneling capture-emission model. The reverse current is proportional to exp( -ilEarl kT)(V D -V )112, where V D is the diffusion voltage andilE ar is a constant. This current is probably limited by generation-recombination process.

Electrotechni cal_ Laboratory L-1,-4 Umezono, Sakura-mura, N'ihari-gun, Ibaraki 305 * 0n leave from Sharp Corporation, 26L3-L lchinomoto-cho, Tenri-c]-ty, Nara 632 We have measured C-V characteristics and temperature dependence of J-V characteristics of undoped a-Si:H heterojunctions formed on p-type c-Si substrates with different resistivities. It has been found out that an abrupt heterojunction model is valid for a-Si:H/p c-Si heterojunctions, and the electron affinity of a-Si:H has been estimated as 3.93 t 0.07 eV from C-V characteristics. The forward cument of all the junctions studied.shows voltage and temperature dependence expressed as exp(-M ^/kT) x exp(Av), where ot". and A are constants independent of vg]{age and templratu?5. in. reverse current is-p*roportional to exp(-AE^-/kT) x (V^_V)'r', where M is constant independent of voltage and temperature and Vo-is the diffusion voltage.

We have investigated the current-voltage characteristics of metal/undoped a-Si: H/n + (or p +) c-Si structures using Mg, Au, Pt and Al. It has been indicated that the energy band of undoped a-Si: H shows a downward bending against Mg, being analogous to n + a-Si: H/undoped a-Si: H contact, while the band shows an upward bending against Au, Pt and Al. Mg/undoped a-Si: H contact is found to allow injection of electrons into the conduction band of a-Si: H, providing us a good ohmic contact property. This contact does not exhibit the thermal-degradation at least up to 100°C.

Investigated are the current-voltage characteristics of metal (Au, Mg)/B-doped hydrogenated amorphous silicon (a-Si:H)/crystalline silicon (n+, p+) diodes for various doping levels of B in a-Si:H. From junction studies we determine the conduction type of B-doped a-Si:H on the basis of ‘‘dominant’’ carrier concentration, and find that the p-n transition occurs at B2H6/SiH4∼10−6 although the conductivity minimum appears at B2H6/SiH4∼10−4.

Japanease d o m e s t i c communications satellite-3(CS-3) were launched by Japanese 11-1