p - Zn O ∕ n - Si heterojunction: Sol-gel fabrication, photoresponse properties, and transport mechanism

Abstract

p - Zn O ∕ n - Si heterojunction is achieved by depositing Al–N codoped p-type ZnO film on n-Si by low-cost sol-gel technique. The junction shows good diode characteristics with rectification ratio (IF∕IR)∼10 at 4V in the dark. The photoresponse of the heterojunction is investigated by studying the current-voltage characteristics under the ultraviolet (370nm) and visible light (450nm) illuminations. By fitting the experimental data, we have proposed the current transport mechanism to be dominated by the recombination tunneling at lower and by the space-charge limited current at higher forward voltages, which are further supported by the photocapacitance and photocurrent spectra.

Nitrogen doped-ZnO/n-GaN heterojunctions

“…The I-V curve of a p-n junction diode can typically be described by an equation,I ¼ I s exp qV=nkT ð ÞÀ1 ½ , where n is the ideality factor and I s is the reverse saturation current. 15,30,31 The obtained ideality factor for the region 0.01-0.4 V is n ¼ 3.1. This is lower than that previously reported for p-ZnO/n-Si heterojunction ($4), 13 and significantly lower than that previously reported a ZnO homojunction diode ($24).…”

“…At higher bias voltages, dependence I $ V 2 attributed to the space charge limited current is typically observed. 13,15,32 However, fitting the I-V curve in the region 0.4-5 V with exponential function I ¼ a V m resulted in m ¼ 1.44. This is close to a value of m ¼ 1.5 which has been previously observed in different heterojunctions, 31,33,34 and which can occur in the case of double injection of carriers, 31 injection from a point contact, 33 and presence of a trap density gradient.…”

“…P-type conductivity in N:ZnO, grown by variety of methods and with different nitrogen sources, has been reported to date. [9][10][11][12][13][14][15][16] In addition, in spite of the concerns on the reproducibility and stability of p-type doping in ZnO, 1,4 stable p-type conductivity for five months of storage in air was reported for N:ZnO. 9 Consequently, nitrogen doping for the achievement of p-type ZnO has significant potential, provided that native and other compensating defects can be controlled to avoid compensation.…”

“…1,3,4 Among different possible acceptor dopants for ZnO, nitrogen has been regarded as one of the most suitable acceptors due to its similar atomic size and electronic structure to oxygen, 3 and hence, it has been extensively studied. [5][6][7][8][9][10][11][12][13][14][15][16] However, p-type conductivity in N:ZnO remains controversial. 3,4 Recent theoretical calculations indicated that nitrogen is a deep acceptor, 5 although hole binding energy derived from PL experiments on N:ZnO was comparable to that observed for Mg in GaN, 4 indicating that nitrogen is a shallow acceptor.…”

Study on the Synthesis, Characterization of p-CuSCN/n-Si Heterojunction

“…(5), we give the dark current as a function of junction-voltage in forward bias. At forward voltage, the I-V characteristic was deviated from the ideal thermionic emission and behaved as I~V 2 relation, which was attributed to the space-charge limited current (SCLC) conduction [12][13][14][15]. This SCLC mechanism is a normal phenomenon in the wide band gap semiconductors due to single-carrier injection [14,15].…”